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Solved the very best collection of Life Processes Class 10 Science Important Questions and Answers Chapter 6 Pdf from the latest NCERT edition books, It will help you in scoring more marks in CBSE Exams.

Life Processes Class 10 Important Questions with Answers Science Chapter 6

Life Processes Class 10 Important Questions Very Short Answer Type

Question 1.
Name the tissue which transports soluble products of photosynthesis in a plant.   [AI 2008]
Answer:
Phloem tissues

Question 2.
Name the tissue which transports water and mineral in a plant.   [AI 2008]
Answer:
Xylem.

Question 3.
Which pancreatic enzyme is effective in digesting proteins?   [Foreign 2008]
Answer:
Pancreatic trypsin.

Question 4.
Which enzyme, present in saliva breaks down starch?   [Foreign 2008]
Answer:
Salivary amylase.

Question 5.
Name the process by which autotrophs prepare their own food.
Answer:
Photosynthesis.

Question 6.
What would be the consequence of deficiency of haemoglobin in your body?   [CBSE 2013]
Answer:
Hemoglobin is a red pigment which carries oxygen in blood to supply to all the parts of the body. Due to its deficiency the supply of oxygen would be low and the energy released in the body would be also low which may lead to a disease called anemia.

Question 7.
List three characteristics of lungs which make it an efficient respiratory surface.   [CBSE 2013]
Answer:
The three characteristics of the lungs are:

1. Large surface area: Lungs provide a large surface area in the form of alveoli inside for the exchange of gases by diffusion. This helps in the absorption of oxygen.
2. Thin walls: The air sacs/alveoli are thin which allows the quick diffusion of the gases through it.
3. Rich in capillary supply: The alveoli are richly supplied with the capillaries that bring blood with the carbon dioxide and absorbs oxygen.

Question 8.
(a) What is the role of HCl in our stomach?
(b) What is emulsification of fats?
(c) Which protein digesting enzyme is present in pancreactic juice?   [CBSE 2013]
Answer:
(a) The HCl provides acidic medium for the action of enzyme pepsin to act and break down the proteins. It kills the germs, microbes and pathogens that enter the stomach.
(ii) The breaking down of big fat globules into the smaller ones is called emulsification of fats.
(c) Trypsin

Question 9.
List in tabular form three differences between arteries and veins.   [CBSE 2013]
Answer:
Arteries:

• They are deep seated
• They carry oxygenated blood
• They are thick walled so carry blood with lots of pressure

Veins:

• They are superficial
• They carry deoxygenated blood
• They are thin walled and hence carry blood with less pressure.

Question 10.
Which enzyme, present in saliva breaks down starch?   [CBSE 2014]
Answer:
Mention the raw materials required for photosynthesis
Salivary amylase present in saliva breaks down starch.
Raw material required for photosynthesis are:

1. Carbon Dioxide: Plants get CO₂ from atmosphere through stomata.
2. Water: Plants absorb water from soil through roots
3. Sunlight: It is absorbed by the chlorophyll present in the leaves.

Life Processes Class 10 Important Questions Short Answer Type

Question 1.
What process in plants is known as transpiration?   [AI 2008]
Answer:
The loss of water by leaves through small pores called stomata is known as transpiration.

Question 2.
How do autotrophs obtain CO₂ and N₂ to make their food?   [AI 2008]
Answer:
CO₂ is obtained from leaves through stomata pores and N₂ is obtained in combined form, e.g. nitrates, through roots in dissolved form.

Question 3.
Write one function each of the following components of the transport system in human beings.
(a) Blood vessels
(b) Blood platelets
(c) Lymph
(d) Heart   [AI 2008]
Answer:
(a) Blood vessels – Carry blood for transportation from part of the body to other.
(b) Blood platelets – Helps in blood clotting during injury.
(c) Lymph – Carries digested and absorbed fat for transportation.
(d) Heart – It is a pumping machine which pumps blood to reach all the parts of the body.

Question 4.
Write any 3 differences between aerobic and anaerobic respiration.   [AI 2008]
Answer:
Aerobic

1. Takes place in presence of O₂.
2. End products are CO₂ + H₂O + energy.
3. Large amount of energy is released.

Anaerobic:

1. Takes place in absence of oxygen.
2. End products are ethanol + CO₂ + energy.
3. Less amount of energy is released.

Question 5.
What is the role of saliva in the digestion of food?   [AI 2008]
Answer:
It converts insoluble starch into soluble sugar and makes the dry food wet.

Question 6.
How are fats digested in our body? Where does this process take place?    [Foreign 2008]
Answer:
Fats when enter our alimentary canal bile juice emulsifies the fat in small intestine the lipase enzyme produced by pancreas digest it to form fatty acids.

Question 7.
What is the role of acid in our stomach?
Answer:
Acid makes the medium in stomach acidic so as to facilitate the action of pepsin. It also kills germs that enter our stomach with food.

Question 8.
What is the mode of nutrition in human beings?
Answer:
Holozoic mode of nutrition i.e., heterotrophic in nature.

Question 9.
Why do the walls of the trachea not collapse when there is less air in it?   [CBSE 2012]
Answer:
Rings of cartilages are present in trachea. These rings support the trachea and do not allow the trachea to collapse when there is less air in it.

Question 10.
In human alimentary canal, name the site of complete digestion of various components of food. Explain the process of digestion.   [CBSE 2012]
Answer:
The site of complete digestion of carbohydrates, fats, proteins is small intestine.

Process of digestion:
Food is chewed with digestion of starch by the action of salivary amylase present in mouth. The formed bolus passes down the esophagus into the stomach by the action of peristalsis. Gastric juices further acts on food for the digestion of proteins and forms chyme.

Chyme enters the duodenum where digestive enzymes from pancreas and bile juice from liver mixes with it and then passes through small intestine. Absorbtion of nutrients occur in small intestine and reabsorption of water and minerals too.

Question 11.
List the three kinds of blood vessels of human circulatory system and write their functions in tabular form.
Answer:
Arteries:
It carries oxygenated blood away from the heart to all the parts of the body

Veins:
It carries de-oxygenated blood from the different parts of the body to the heart

Capillaries:
The single walled tubes helps in the exchange of materials within the cell and the blood
by diffusion.

Question 12.
Why do herbivores have longer, small intestine than carnivores?   [CBSE 2014]
Answer:
Herbivores feed on the plants and its parts which contain cellulose. Digestion of cellulose takes longer time and hence to allow the complete digestion the small intestine is longer whereas the carnivores eat flesh and meat which does not need cellulose enzyme and long time for digestion.

Question 13.
Write correct sequence in four steps about the method for the preparation of temporary mount of a stained leaf peel.   [CBSE 2014]
Answer:

1. Take a leaf and fold it to remove the lower surface peel with the forceps.
2. Keep the peel in a watch glass containing dilute safranin for staining.
3. Place the leaf on clean glass slide, add a drop of glycerin and gently place a cover slip over it.
4. Remove the extra stain with the blotting paper and observe it under a microscope.

Question 14.
In mammals and birds why is it necessary to separate oxygenated and de-oxygenated blood? [CBSE 2014]
Answer:
In mammals and birds the energy requirement for their life processes is high and hence large amount of oxygen is required to break down the glucose which would supply the energy during cellular respiration. Hence the oxygenated blood is required to supply oxygen to each and every cell and this works efficiently only if the deoxygenated blood is seperated from the oxygenated one.

Question 15.
Draw a neat diagram of excretory system of human beings and label on it:
(i) Left kidney
(ii) Urinary bladder [CBSE 2014]
Answer:

Question 16.
Draw a diagram of human respiratory system and label on it:
(i) Diaphragm
(ii) Larynx
(iii) Trachea   [CBSE 2014]
Answer:

Question 17.
(a) Name the site of exchange of material between the blood and surrounding cells
(b) Draw a schematic representation of transport and exchange of oxygen and carbon dioxide in human body.   [CBSE 2014]
Answer:
(a) Capillaries
(b)

Question 18.
What are enzymes? Name any one enzyme of our digestive system and write its function.   [CBSE 2015]
Answer:
Enzymes are biological catalysts that increase the rate of chemical reactions without being used up. For example: Amylase catalyses helps in the breakdown of starch into sugars in the mouth and small intestine.

Question 19.
(i) Write the balanced chemical equation for the process of photosynthesis.
(ii) When do the desert plants take up carbon dioxide and perform photosynthesis?
Answer:
(i) Photosynthesis can be represented using a chemical equation. The overall balanced equation is

(ii) Desert plants open up their stomata during night and take in CO₂. Stomata remains closed during the day time to prevent the loss of water by transpiration. They store CO₂ in their cells until the sun comes out and they can carry on with photosynthesis during the day time.

Question 20.
In single-celled organisms diffusion is sufficient to meet all their requirements of food, exchange of gases or removal of wastes but it is not in case of multicellular organisms. Explain the reason for this difference.    [CBSE 2015]
Answer:
Unicellular organisms can absorb sufficient oxygen because of its complete contact with the atmosphere, but in multicellular organisms the rate of absorption and diffusion becomes very less because all cells are not in direct contact with the atmosphere. Multicellular organisms require greate amount of oxygen to sustain life processes which cannot be fulfilled by the process of diffusion.

Question 21.
Draw a diagram of human excretory system and label kidneys, ureters on it.    [CBSE 2015]
Answer:

Question 22.
Name the acid present in the following:
(i) Tomato
(ii) Vinegar
(iii) Tamarind   [CBSE 2015]
Answer:
(i) Oxalic acid
(ii) citric acid
(iii) Tartaric acid.

Question 23.
State the role of the following in human digestive system:
(i) Digestive enzymes
(ii) Hydrochloric acid
(iii) Villi    [CBSE 2015]
Answer:
(i) Digestive enzymes – Foods need to be broken into their small or simpler molecules so that they can be absorbed into the bloodstream. However, the physical breakdown of food is not enough. Enzymes are hence needed for the chemical breakdown of food and speeding up the digestive process. The products of digestion should be smaller enough to be absorbed.

(ii) Hydrochloric acid helps to kill the germs which might have entered into the system through food. It creates acidic medium for the pepsin to act on food to break down proteins.

(iii) Villi are finger like projections in the small intestine. They help to increase the surface area for absorption of the digested food. Villi are richly supplied with blood vessel which help to absorb digested food from the blood stream.

Life Processes Class 10 Important Questions Long Answer Type

Question 1.
(a) Draw a diagram depicting human alimentary canal and label on it gall bladder, liver and pancreas.
(b) State the roles of liver and pancreas.
(c) Name the organ which performs the following functions in human:
(i) Absorption of digested food.
(ii) Absorption of water.    [AI 2008]
Answer:
(a)

(b) Liver – It secretes bile juice which makes medium alkaline and emulsifies the fat.
Pancreas – It secretes pancreatic juice which contains amylase, lipase and trypsin.
Amylase digest carbohydrates
Lipase digest fats
Trypsin digest proteins

(c) (i) Villi in small intestine absorbs digested food.
(ii) Large intestine absorbs water.

Question 2.
(a) Name two different ways in which glucose is oxidised to provide energy in various organisms.
(b) Write any two differences between the two ways of oxidation of glucose in organisms.   [AI 2008]
Answer:
(a) Breakdown of glucose by various pathways for different organisms are:

(b) Difference in oxidation of glucose
Aerobic:

1. Glucose is oxidised in presence of O₂.
2. End products are CO₂ + H₂O + Energy.
3. Large amount of energy is released.

Anaerobic:

1. Oxidised in absence of O₂.
2. End products are Ethanol + CO₂ + Energy.
3. Less amount of energy is released.

Question 3.
(a) How do autotrophs prepare food?
(b) List three events which occur during this process.
(c) State two sources from which plants obtain nitrogen for the synthesis of proteins and other compounds.   [Foreign 2008]
Answer:
(a) Autotrophs prepare their own food by photosynthesis and few by chemotropism.

(b) Events occurring during Photosynthesis:

• Absorption of light energy by chlorophyll.
• Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
• Reduction of carbon dioxide into carbohydrates.

(c) Plants obtain nitrogen from the soil in dissolved form of nitrates or nitrites. Rhizobium bacteria converts atmospheric nitrogen into organic compounds.

Question 4.
What are stomata? Draw a labelled diagram of stomata. Write two functions of stomata.   [Foreign 2008]
Answer:
Stomata are small pores present on the leaves underside.

Two functions of stomata:

1. Allows the exchange of gases, O₂ and CO₂.
2. It helps in losing extra water by transpiration and creates suction pull which helps the water to rise in xylem.

Question 5.
(a) Draw a diagram of human alimentary canal and label on it.
Oesophagus, gall bladder, liver and pancreas.
(b) Explain the statement, “Bile does not contain any enzyme but it is essential for digestion.”    [AI 2009]
Answer:
(a)

(b) Bile does not contain any enzyme, but it makes the medium in small intestine basic so that trypsin acts on proteins in this medium.
It emulsifies fat i.e., breaks large globules of fat into smaller ones.

Question 6.
(a) Draw a diagram of excretory system in human being and label on it.
Aorta, Vena cava, Urinary bladder, Urethra.
(b) List two vital functions of the kidney.
Answer:
(a)

(b) Kidney helps in
(i) Excretion of waste from the body and
(ii) Osmoregulation, maintain the level of water in the body.

Question 7.
(a) Draw a sectional view of human heart and label on it aorta, pulmonary vein, vena cava, left ventricle.
(b) Why is double circulation of blood necessary in human being?    [AI 2009]
Answer:
(a)

(b) The blood passes through the heart twice. Right side of the heart receives deoxygenated blood which is circulated to lungs for purification. At the same time the left side of the heart receives oxygenated blood which is circulated to the body. This is called double circulation.

Question 8.
(a) Draw the structure of a nephron and label the following on it: glomerulus, bowman’s capsule, renal artery, collecting duct.
(b) What happens to glucose that enters the nephron along with filtrate?
Answer:
(a)

(b) The glucose that enters the nephron along with filtrate is reabsorbed by the blood capillaries.

Question 9.
(a) Draw a diagram of the human respiratory system and label on it alveolar sac, bronchioles, larynx and trachea.
(b) How are the lungs designed in human beings to maximise the area of exchange of gases?   [Foreign 2009]
Answer:
(a)

(b) Lungs have bronchioles (small tubes) coming from the bronchi. The bronchioles at the terminals form a balloon like structure called alveoli which increases the surface area for exchange of gases and is richly supplied with blood capillaries.

Question 10.
(a) Draw a diagram to show open stomatal pore and label on it:
(i) guard cells
(ii) chloroplast
(b) State two functions of stomata.
(c) How do guard cells regulate the opening and closing of stomatal pore?   [CBSE 2012]
Answer:
(a) Open stomatal

(b) (i) It helps in the exchange of gases like carbon dioxide and oxygen as per the requirement for the photosynthesis and respiration of the plants.
(ii) It also helps in the loss of water in the form of water vapour called transpiration.

(c) Guard cells swell when water enters into it by the process of osmosis and thereby opens the stomata pore for the loss of the water.
When the water is lost it shrinks and closes the stomata pore.

Question 11.
(a) Draw a diagram of human respiratory system and label the following:
(i) part where air is filtered by fine hair and mucus
(ii) part which terminates in balloon-like structures
(iii) balloon-like structures where exchange of gases takes place.
(iv) part which separates chest cavity from abdominal cavity.
(b) Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms? [CBSE 2012]
Answer:
(a)

(b) The oxygen dissolved in water is very less and the aquatic animals do not get sufficient oxygen unless they breathe fast to meet their energy needs.

Question 12.
Draw a diagram of human excretory system and label kidney, ureter, renal artery and urethra. State in brief the function of:
1. renal artery
2. kidney
3. ureter
4. urinary bladder   [CBSE 2013]
Answer:
(a)

Functions:

1. Renal artery: It brings the impure blood to the kidneys for the purification.
2. Kidney: The kidneys purify the blood by removing the waste from it and regulates the body’s fluid volume and mineral composition by reabsorbing the water and required electrolytes.
3. Ureter: It is a tube that carries urine from the kidney to the urinary bladder.
4. Urinary bladder: It is a muscular sac that stores urine before it is excreted.

Question 13.
(a) Draw a diagram of excretory system in human beings and label the following parts. Aorta, kidney, urinary bladder and urethra.
(b) How is urine is produced ans eliminated?
Answer:
(a)

(b) Urine is produced by the filtration of blood by the kidneys. It is then passed through the ureters to urinary bladder where it is stored till urination. Once a person feel like urinating it is passed to urethra to get eliminated from the body.

Question 14.
(a) Explain how does the exchange of gases occur in plants across the surface of stems, roots and leaves.
(b) How are water and minerals transported in plants? [CBSE 2015]
Answer:
(a) In plants there are tiny pores called stomata on leaves and lenticels in stem which facilitate the exchange of gases. Carbon dioxide is taken in and oxygen is given out during photosynthesis and vice versa during respiration.

(b) Water and minerals are transported within the plant by the xylem vessels mainly in an upward direction.
Phloem transports the products of photosynthesis within the plant, to all parts like the stem, roots fruits etc. in all directions.

Solved the very best collection of Periodic Classification of Elements Class 10 Science Important Questions and Answers Chapter 5 Pdf from the latest NCERT edition books, It will help you in scoring more marks in CBSE Exams.

Periodic Classification of Elements Class 10 Important Questions with Answers Science Chapter 5

Periodic Classification of Elements Class 10 Important Questions Short Answer Type

Question 1.
What physical and chemical properties of elements were used by Mendeleev in creating his Periodic Table? List two observations which posed a challenge to Mendeleev’s Periodic Law.   (CBSE 2008)
Answer:
The physical property used was the atomic mass of an element.
The chemical property used was the nature of oxide and hydride formed i.e., similarity in chemical properties were used by Mendeleev.

The two observations that posed challenge in Mendeleev Periodic Law were:

1. Arranging elements according to the increasing order of atomic mass could not be maintained. Chemical properties do not depend on atomic mass.
2. Isotopes were not given any place in the table as they have different atomic mass but same chemical properties.

Question 2.
Table given below shows a part of the Periodic Table.

Using this table explain why?
(a) Li and Na are considered as active metals.
(b) Atomic size of Mg is less than that of Na.
(c) Fluorine is more reactive than chlorine.   (Foreign 2008)
Answer:
(a) Li and Na can readily lose electrons due to bigger size of atom.
(b) Mg has more number of protons than Na which attracts the electrons thereby reducing the size of Mg.
(c) Fluorine readily accepts/gains electrons to become F^– ion due to its small atomic size as compared to chlorine.

Question 3.
The position of three elements A, B and C in the Periodic Table are shown below:

Giving reasons, explain the following:
(а) Element A is a non-metal.
(б) Element B has a larger atomic size than element C
(c) Element C has a valency of 1.   (Foreign 2008)
Answer:
(a) A is a non-metal because it can gain electrons easily, it has 7 valence electrons and form negative ions to become stable.
(b) The atomic number of B is less than C, it has less nuclear charge, less force of attraction between protons in the nucleus and valence electrons, hence its size is bigger than C.
(c) Element ‘C’ has 7 valence electrons, it can gain 1 electron to become stable so its valency is 1.

Question 4.
The position of three elements A, B and C in the Periodic Table are shown below:

Period	Group I	II	III
1	–	–	–
2	–	–	B
3	A	C	–

Giving reason, explain the following:
(a) Element A is a metal.
(b) Element C has a larger size than B.
(c) Element B has a valency of 3.   (Foreign 2008)
Answer:
(a) ‘A’ is a metal because its valence electron is 1, it can readily lose electron to became stable.
(b) Element ‘C’ belongs to 3rd period it has 3 shells whereas ‘B’ has only 2 shells, it belongs to 2nd period, distance between nucleus and valence electrons is more in C, hence its size is bigger than B.
(c) ‘B’ belongs to III group, has 3 valence electrons, it can lose 3 electrons to become stable hence its valency is 3.

Question 5.
The elements of the second period of the Periodic Table are given below:

Li

Be

B

C

N

O

F

(a) Give reason to explain why atomic radii decreases from Li to F.
(b) Identify the most
(i) Metallic and
(ii) Non-metallic element.  (AI, Foreign 2008)
Answer:
(a) In a period on moving from left to right, the atomic number increases, the number of shells remains the same, nuclear charge increases the force of attraction on electrons towards the nucleus. The valence electrons are pulled at the centre, hence atomic radii decreases from Li to F.

(b) (i) Most metallic element → Li
(ii) Most non-metallic element → F.

Question 6.
(a) What is meant by periodicity in properties of elements with reference to the Periodic Table?
(b) Why do all the elements of the same group have similar properties?
(c) How will the tendency to gain electrons change as we go from left to right across a period? Why?   (AI 2009)
Answer:
(a) The repetition of same properties after definite interval is called periodicity in properties.
(b) It is because all elements in a group have same valence electrons.
(c) Tendency to gain electrons increases from left to right in the period because the atomic size goes on decreasing and nuclear charge increases, which can attract the nearby electron.

Question 7.
An element ‘X’ has atomic number 13.
(a) Write its electronic configuration,
(b) State the group to which ‘X’ belongs.
(c) Is ‘X’ a metal or a non-metal?
(d) Write the formula of its bromide.   (CBSE 2012)
Answer:
(a) 2, 8, 3
(b) Group 13
(c) ‘X’ is a metal.

Question 8.
State the Modern Periodic Law for classification of elements. How many
(a) Groups and
(b) periods are there in the Modem Periodic Table?    (CBSE 2012)
Answer:
‘Properties of elements are the periodic function of their atomic number’.
(a) There are 18 groups and
(b) 7 periods in the Modern Periodic Table.

Question 9.
An element ‘M’ has atomic number 11.
(a) Write its electronic configuration,
(b) State the group to which ‘M’ belongs.
(c) Is ‘M’ a metal or a non-metal?
(d) Write the formula of its chloride.   (CBSE 2012)
Answer:
(a) 2, 8, 1
(b) Group 1
(c) ‘M’ is a metal.

Question 10.
An element ‘M’ has atomic number 12.
(a) Write its electronic configuration.
(b) State the group to which ‘M’ belongs,
(c) Is ‘M’ a metal or a non-metal?
(d) Write the formula of its oxide.   (CBSE 2012)
Answer:
(a) 2, 8, 2
(b) Group 2
(c) M is a metal.

Question 11.
The formula of magnesium oxide is MgO. State the formula of barium nitrate and barium sulphate, if barium belongs to the same group as magnesium.   (CBSE 2012)
Answer:

Question 12.
Choose the answer from the following: Ca -20, Li -3, Na -11, Ne -10
(a) An element having two shells completely filled with electrons
(b) Two elements belonging to the same group of the periodic table.   (CBSE 2012)
Answer:
(a) Ne -10 has electronic configuration as 2, 8 and its both the shells are completely filled.
(b) Elements Li -3 and Na -11 belong to the same group as both these elements has same valence electrons i.e., one and belong to group 1.

Question 13.
Why do all the elements of the
(a) same group have similar properties,
(b) same period have different properties? (CBSE 2012)
Answer:
(a) Elements of same group have similar properties due to same number of valence electrons, that is, they have same valency.
(b) Elements of same period have different properties as they differ in number of valence electrons.

Question 14.
An element ‘E’ has following electronic configuration:

K	L	M
2	8	6

(a) To which group of the periodic table does element ‘E’ belong?
(b) To which period of the periodic table does element ‘E’ belong?
(c) State the number of valence electrons present in element ‘E’.
(d) State the valency of the element ‘E’.   (CBSE 2012)
Answer:
(a) ‘E’ belongs to group 16.
(b) It belongs to 3rd period.
(c) It has 6 valence electrons,
(d) Its valency is equal to 2.

Question 15.
An element has atomic number 13.
(a) What is the group and period number to which this element belongs?
(b) Is this element a metal or a non-metal? Justify your answer.   (CBSE 2012)
Answer:
(a) It belongs to group 13 and 3rd period.
(b) It is a metal because it can lose 3 electrons to become stable.

Question 16.
The electronic configuration of two elements ‘A’ and ‘B’ are 2, 8, 7 and 2, 8, 8, 2, respectively. Write the atomic number of these elements. What will be formula of the compound formed and the nature of bond between them when these two elements chemically combine together?   (CBSE 2012)
Answer:
‘A’ has atomic number 17. Its electronic configuration is 2, 8, 7. Its valency is equal to 1. ‘B’ has atomic number 20. Its electronic configuration is 2, 8, 8, 2. Its valency is 2.

Ionic bond will be formed to form compound AB₂.

Question 17.
The atomic numbers of three elements are given below:

Element (symbol)	A	B	C
Atomic number	3	6	9

Write the symbol of the element which belongs to (a) group 1, (b) group 14, of the periodic table. State the period of the periodic table to which these elements belong. State reason to support your answer.   (CBSE 2012)
Answer:
(a) A belongs to group 1.
(b) B belongs to group 14.
These elements belong to second period because these elements have two shells. A has electronic configuration 2, 1 and has one valence electron so, belongs to group 1. ‘B’ has electronic configuration 2, 4 and has four valence electrons so, belongs to group 14 and period 2. ‘C’ has electronic configuration 2, 7 and has seven valence electrons. All of them contain two shells and so belong to second period.

Question 18.
Na, Mg and Al are the elements having one, two and three valence electrons respectively. Which of these elements (a) has the largest atomic radius,
(b) is least reactive?
Justify your answer stating reason for each.   (CBSE 2012)
Answer:
(a) Na has the largest atomic radius because on moving from Na to Al effective nuclear charge increases which causes decrease in atomic radius.
(b) Al is least reactive because it has smallest atomic size. It has greater effective nuclear charge, therefore, cannot lose electrons easily, hence it is least reactive.

Question 19.
(a) How are the following related?
(i) Number of valence electrons of different elements in the same group.
(ii) Number of shells of elements in the same period.
(b) How do the following change?
(i) Number of shells of elements as we go down a group.
(ii) Number of valence electrons of elements on moving from, left to right in a period.
(iii) Atomic radius in moving from left to right along a period.
(iv) Atomic size down a group. (CBSE 2012)
Answer:
(a) (i) Different elements in same group have same number of valence electrons.
(ii) Number of shells of elements in same period are equal.

(b) (i) Number of shells of elements goes on increasing down the group.
(ii) Number of valence electrons of elements goes on increasing on moving from left to right in a period.
(iii) Atomic radius goes on decreasing on moving from left to right along a period.
(iv) Atomic size goes on increasing down a group.

Question 20.
(a) How many periods are there in the Modern Periodic Table of elements?
(b) How do atomic radius, valency and metallic character vary down a group?
(c) How do the atomic size and metallic character of elements vary as we move from left to right in a period?   (CBSE 2012)
Answer:
(a) There are 7 periods.
(b) Atomic radius goes on increasing down the group. Valency remains same. Metallic character increases down the group.
(c) Atomic size decreases along a period from left to right. Metallic character decreases along a period from left to right.

Question 21.
How many groups and periods are there in the modem periodic table? How do the atomic size and metallic character of elements vary as we move:   (Delhi 2015)
(a) down a group, and
(b) from left to right in a period
Answer:
18 groups, 7 periods
(a) Atomic size increases and metallic character increases.
(b) Atomic size decreases and metallic character decreases.

Question 22.
From the following elements :
4Be; 9F; 19K; 20Ca
(i) select the element having one electron in the outermost shell.
(ii) two elements of the same group.
Write the formula of and mention the nature of the compound formed by the union of 19K and element X(2, 8, 7).        (Delhi 2015, CBSE 2012)
Answer:
(i) K/Potassium
(ii) Be and Ca.
KX or KCl is formed by union of K and X which is ionic/electrovalent in nature.

Question 23.
The atomic number of an element ‘X’ is 20.
(i) Determine the position of the element ‘X’ in the periodic table.
(ii) Write the formula of the compound formed when ‘X’ reacts/combines with another element ‘Y (atomic number 8).
(iii) What would be the nature (acidic or basic) of the compound formed ? Justify your answer.   (Foreign 2015)
Answer:
Electronic configuration : 2, 8, 8, 2.
(i) ‘X’ is present in the 2nd group and 4th period of the periodic table.
(ii) Y (2, 6) has valency 2. Thus, an atom of Y accepts 2 electrons from X to form XY.
(iii) Basic because X is a metal and the oxides of metals are basic in nature. (Y, Atomic number = 8, oxygen)

Question 24.
Taking the example of an element of atomic number 16, explain how the electronic configuration of the atom of an element relates to its position in the modem periodic table and how valency of an element is calculated on the basis of its atomic number.   (AI 2015)
Answer:
Electronic configuration of element with atomic no. 16 is 2, 8, 6.
Since it has 3 shells, the period no. will be 3.
Since the no. of valence electrons is 6, the group no. will be 10 + 6 = 16.
Valency of the element will be 8- valence electrons i.e., 8 – 6 = 2.

Question 25.
Two elements ‘P’ and ‘Q’ belong to the same period of the modern periodic table and are in Group-1 and Group-2 respectively. Compare their following characteristics in tabular form :   (AI 2015)
(a) The number of electrons in their atoms
(b) The sizes of their atoms
(c) Their metallic characters
(d) Their tendencies to lose electrons
(e) The formula of their oxides
(f) The formula of their chlorides
Answer:

Question 26.
Calcium is an element with atomic number 20. Stating reason answer each of the following questions:   (Delhi 2016)
(a) Is calcium a metal or non-metal?
(b) Will its atomic radius be larger or smaller than that of potassium with atomic number 19?
(c) Write the formula of its oxide.
Answer:
(a) It is a metal. Since it has two electrons in its outermost shell/two valence electrons, which it can lose easily.
(b) K(19) is placed before Ca(20) in the same period/fourth period. Since the atomic radius decreases on moving from left to right along a period, the atomic radius of calcium is smaller than that of potassium.
(c) The formula of oxide of calcium is CaO, because the valency of calcium as well as that of oxygen is 2.

Question 27.
An element ‘M’ with electronic configuration (2, 8, 2) combines separately with (NO₃)^–, (SO₄)^2- and (PO₄)^3- radicals. Write the formula of the three compounds so formed. To which group and period of the Modern Periodic Table does the elements ‘M’ belong? Will ‘M’ form covalent or ionic compounds? Give reason to justify your answer. (Delhi 2016)
Answer:

• The electronic configuration (2, 8, 2) of the element ‘M’ suggests that it belongs to group 2 and period 3 of the Modern Periodic Table and its valency is 2.
• The chemical formula of the compounds are
  M(NO₃)₂/Mg(NO₃)₂; MSO₄/MgSO₄; M₃(PO₄)₂ / Mg₃(PO₄)₂.
• ‘M’ will form ionic compounds by losing two electrons.

Question 28.
Write the main aim of classifying elements. Name the basic property of elements used in the development of Modern Periodic Table. State the Modern Periodic Law. On which side (part) of the Modern Periodic Table do you find metals, metalloids and non-metals?   (Foreign 2016, 2015)
Answer:
For systematic and simplified study of elements and their compounds.
Basic property: Atomic Number.

Modern periodic Law: The properties of elements are a periodic function of their atomic number.
Metals are found on the left side and centre of the Modern Periodic Table. Metalloids are found in a zig-zag manner between the metals and the non-metals. Non-metals are found on the right side of the Modern Periodic Table.

Question 29.
An element ‘X’ belongs to 3^rd period and group 16 of the Modern Periodic Table.   (AI 2016)
(a) Determine the number of valence electrons and the valency of ‘X’.
(b) Molecular formula of the compound when ‘X’ reacts with hydrogen and write its electron dot structure.
(c) Name the element ‘X’ and state whether it is metallic or non-metallic.
Answer:
(a) Electronic configuration of X – 2, 8, 6.
Valence electrons – 6
Valency = 8 – 6 = 2
(b) Formula with hydrogen – H₂X or H₂S

(c) Sulphur; Non-Metal.

Question 30.
An element ‘X’ has mass number 35 and number of neutrons 18. Write atomic number and electronic configuration of ‘X’. Also write group number, period number and valency of ‘X’.    (AI 2016)
Answer:
Atomic number of X = Mass number of X – No of neutrons = 35 – 18 = 17
Therefore Electronic configuration of X = 2, 8, 7
Group number =17
Period no = 3
Valency = 8 – 7 = 1

Question 31.
Choose from the following elements to answer the questions given below:
₆C, ₈O, ₁₀Ne, ₁₁Na, ₁₄Si
(a) Elements that should be in the same period
(b) Elements that should be in the same group
State reason for the selection in each case.    (Delhi 2016)
Answer:
The electronic configuration of all given elements is:
C = 2, 4
O = 2, 6
Ne = 2, 8
Na = 2, 8, 1
Si = 2, 8, 4
(a) Elements C, O and Ne are in the same period, as all of them have electrons occupying the first two shells. The elements Na and Si will be in the same 3rd period as both of them has electrons occupied in 3 shells.
(b) Elements C and Si will be in the same group because both these elements have same number of valence electrons that is 4.

Periodic Classification of Elements Class 10 Important Questions Long Answer Type

Question 1.
On the basis of the table of Mendeleev’s Periodic Table
(a) Name the element which is in
(i) I group and 3rd period.
(ii) VII group and 2nd period.
(b) Suggest the formula for the following:
(i) Oxide of nitrogen
(ii) Hydride of oxygen
(c) In group VIII of Periodic Table, why does cobalt with atomic mass 58.93 appear before nickel having atomic mass 58.71?
(d) Besides gallium, which two other elements have since been discovered for which Mendeleev had left gaps in his Periodic Table?
(e) Using atomic masses of Li, Na and K, find the average atomic mass of Li, and K and compare it with the atomic mass of Na. State the conclusion drawn from this activity.
Answer:
(a) (i) Sodium (ii) Fluorine
(b) (i) N₂O₅ (ii)H₂O
(c) Co resembles with Rh and Ir whereas ‘Ni’ resembles with Pd and Pt.
(d) Germanium and scandium

The atomic mass of Na is the average atomic mass of Li and K and these elements resemble with each other.

Question 2.
(a) Why do we classify elements?
(b) What were the two criteria used by Mendeleev in creating his Periodic Table?
(c) Why did Mendeleev leave some gaps in his Periodic Table?
(d) In Mendeleev’s Periodic Table, why was there no mention of Noble gases like Helium, Neon and Argon?
(e) Would you place two isotopes of chlorine Cl-35 and Cl-37 in different slots because of their different atomic masses or in the same slot because their chemical properties are the same? Justify your answers.    (AI 2008)
Answer:
(a) Classification is done to study the properties of elements conveniently.
(b) Increasing order of atomic mass and similarity in chemical properties i.e. the nature of oxide and hydride formed.
(c) The gaps were left for undiscovered elements then.
(d) Noble gases were not invented at that time.
(e) Cl – 35 and Cl – 37 will be kept in the same slot as their chemical properties are same.

Question 3.
(a) What are ‘groups’ and ‘periods’ in the Periodic Table?
(b) Two elements M and N belong to groups I and II respectively and are in the same period of the Periodic Table. How do the following properties of M and N vary?
(i) Sizes of their atoms.
(ii) Their metallic characters.
(iii) Their valencies in forming oxides.
(iv) Molecular formulae of their chlorides.    (Foreign 2009)
Answer:
(a) The vertical column in the Periodic Table are called ‘groups’, the horizontal rows in the table are called periods.

(b) (i) ‘M’ and ‘N’ belong to the same period but group I and II respectively. N is smaller than M as the atomic size decreases on moving from left to right across the Periodic Table.
(ii) M is more metallic than ‘N’ because metallic character decreases from left to right as tendency to lose electrons decreases due to decrease in atomic size.
(iii) The valencies of M and N are 1 and 2 respectively, valency across the period first increases then decreases.
(iv) MCl and NCl₂.

Question 4.
(a) Which 2 criteria did Mendeleev use to classify the elements in his table?
(b) State Mendeleev’s Periodic law.
(c) Why could no fixed position be given to hydrogen in Mendeleev’s Periodic Table?
(d) How and why does the atomic size vary as you go:
(i) From left to right along a period
(ii) Down a group?   (CBSE 2009)
Answer:
(a) Increasing order of atomic mass and similarities in chemical properties of elements i.e., the formula of oxides and hydrides formed by elements.
(b) Mendeleev’s Periodic Law → Properties of elements are periodic functions of their atomic masses.

(c) Hydrogen had no fixed position in Mendeleev’s Periodic table because it resembles alkali metals by forming positive ions and resembles halogens by forming diatomic molecule.

(d) (i) Atomic size decreases from left to right, as the valence electrons are attracted by the nucleus due to increase in the nuclear force.
(ii) The atomic size increases from top to bottom in a group because -the number of shells keep on increasing therefore distance between nucleus and valence electrons increases.

Question 5.
(a) Why did Mendeleev left gaps in his Periodic Table?   (CBSE 2009)
(b) State any 3 limitations of Mendeleev’s classification.
(c) How does electronic configuration of atoms change in period with increase in atomic number?
Answer:
(a) Mendeleev left some gaps for undiscovered elements, because he predicted that there would be such elements which will fit in the gaps in future. He also predicted the properties of these elements.
(b) 3 limitations are:

1. Position of hydrogen was not justified.
2. Increasing order of atomic mass could not be maintained.
3. Isotopes were not given separate place as they have different atomic mass.

(c) In a period the valence electrons goes on increasing from left to right as the number of shells is same.

Question 6.
An element ‘X’ (Atomic number = 20) burns in the presence of oxygen to form a basic oxide.   (Foreign 2016)
(a) Identify the element and write its electronic configuration.
(b) State its group number and period number in the Modern Periodic Table.
(c) Write a balanced chemical equation for the reaction when this oxide is dissolved in water.
Answer:
(a) X(20) – 2, 8, 8, 2. It is calcium.
(b) Second group, fourth period
(c) CaO + H₂O → Ca(OH)₂.

Solved the very best collection of Carbon and its Compounds Class 10 Science Important Questions and Answers Chapter 4 Pdf from the latest NCERT edition books, It will help you in scoring more marks in CBSE Exams.

Carbon and its Compounds Class 10 Important Questions with Answers Science Chapter 4

Carbon and its Compounds Class 10 Important Questions Very Short Answer Type

Question 1.
How many covalent bonds are there in a molecule of ethane (C₂H₆)?  (CBSE 2011)
Answer:
There are 7 covalent bonds in a molecule of ethane.

Question 2.
Write the electron dot structure of ethane molecule (C₂H₄).   (CBSE 2011)
Answer:

Question 3.
Write the electron dot structure of ethane molecule (C₂H₆).   (CBSE 2011)
Answer:

Question 4.
Draw the structure of butanone molecule, CH₃COC₂H₅.   (CBSE 2011)
Answer:

Question 5.
Draw the structure of the hexanal molecule, C₅H₁₁CHO.    (CBSE 2011)
Answer:

Question 6.
Butanone is a four carbon per molecule compound. Name the functional group present in it.   (CBSE 2011)
Answer:
Ketone

Question 7.
Name the following compound:   (CBSE 2011)

Answer:
1-Hexyne is IUPAC name of the compound.

Question 8.
Name the functional group present in each of the following organic compounds:
(i) C₂H₅Cl
(ii) C₂H₅OH   (CBSE 2012)
Answer:
(i) (- Cl) Halogen (Chloro)
(ii) (- OH) Alcohol

Question 9.
Name the functional group present in each of the following compounds:
(i) HCOOH
(ii) C₂H₅CHO   (CBSE 2012)
Answer:
(i) – COOH (Carboxylic acid)
(ii) – CHO (Aldehyde)

Question 10.
Name the functional group present in each of the following organic compounds:
(i) CH₃COCH₃
(ii) C₂H₅COOH   (CBSE 2012)
Answer:

(ii) Carboxylic acid (—COOH)

Question 11.
Write the name and formula of the second member of the carbon compounds having functional group —OH.   (CBSE 2012)
Answer:

Question 12.
Write the name and formula of the first member of the carbon compounds functional group —CHO.   (CBSE 2012)
Answer:

Question 13.
Write the name and formula of the first member of the carbon compounds having functional group —COOH.   (CBSE 2012)
Answer:

Question 14.
Write the name and formula of the 2nd member of the series of carbon compounds whose general formula is C₂H_2n+1OH   (CBSE 2012)
Answer:
Ethanol, C₂H₅OH or CH₃CH₂OH

Question 15.
Write the name and formula of the 2nd member of the series of carbon compounds whose general formula is C_nH_2n.   (CBSE 2012)
Answer:
C₃H₆, H₂C = CH – CH₃.
Propene is second member of series whose general formula is C_nH_2n.

Question 16.
Write the name and formula of the 2nd member of homologous series having general formula C_nH_2n.   (Delhi 2015)
Answer:
Propene C₃H₆

Question 17.
Name the process by which unsaturated fats are changed to saturated fats.    (Foreign 2015)
Answer:
Hydrogenation.

Question 18.
Write the number of covalent bonds in the molecule of ethane.   (AI 2015)
Answer:
Seven.

Question 19.
Write the next homologue of each of the following:    (Delhi 2016)
(i) C₂H₄
(ii) C₄H₆
Answer:
(i) C₃H₆
(ii) C₅H₈

Question 20.
Which element exhibits the property of catenation to maximum extent and why?   (Foreign 2016)
Answer:
Carbon, Due to strong C—C bond.

Question 21.
Write the name and structure of an alcohol with three carbon atoms in its molecule.   (AI 2016)
Answer:

Question 22.
While cooking, if bottom of the vessel is getting blackened on the outside, what does is mean? (Delhi 2017)
Answer:
It means fuel is not burning completely.

Carbon and its Compounds Class 10 Important Questions Short Answer Type

Question 1.
(a) Complete the following equations:

(b) Write the name of the following:
(i) CH₃CH₂COOH
(ii) CH₃CH₂Br
(c) Draw the electron dot structure of ethene(C₂H₄).   (CBSE 2008C)
Answer:
(a)

(b) (i)Propanoic acid
(ii) Bromoethane
(c) Electron dot structure of ethene

Question 2.
(a) Name the compound CH₃CH₂OH and identify its functional group.
(b) Give a chemical test to distinguish between ethanol and ethanoic acid.
(c) Name the product formed when an organic acid reacts with an alcohol in presence of an acid catalyst. What is the name assigned to this type of reaction? (AI 2008C)
Answer:
(a) CH₃CH₂OH – Ethanol; Functional group: alcohol (-OH)

(b) Take ethanol and ethanoic acid in two different test tubes. Add sodium carbonate/ sodium hydrogen carbonate solution in both the test tubes, the test tube which will produce brisk effervescence of CO₂ gas will contain ethanoic acid. Ethanol do not evolve CO₂ gas when reacted with Na₂CO₃/NaHCO₃.

(c) When an organic acid reacts with an alcohol in presence of an acid as catalyst, it produces fruity smelling compound called ester. Such a reaction is called esterification.
Example:

Question 3.
(a) Give a chemical test to distinguish between saturated and unsaturated hydrocarbons.
(b) (i) Name the products formed when ethanol burns in air.
(ii) What two forms of energy are liberated on burning alcohol?
(c) Why is the reaction between methane and chlorine considered a substitution reaction?   (AI 2008C)
Answer:
(a) On adding bromine water, the unsaturated hydrocarbon decolourises the bromine
water but the saturated hydrocarbon will not decolourise bromine water.

(b) (i) Ethanol burns in air to produce carbon dioxide and water.
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O + heat + light
(ii) Two forms of energy obtained are heat energy and light energy.

(c) When methane reacts with chlorine, the hydrogen atom of methane is replaced by chlorine atom step by step and hence it is termed as substitution reaction.
CH₄ + Cl₂ → CH₃Cl + HCl

Question 4.
(a) Name the compound CH₃COOH and identify its functional group.
(b) Give a chemical test to identify this compound.
(c) Name the gas evolved when this compound acts on solid sodium carbonate. How would you identify this gas?  (AI 2008C)
Answer:
(a) Ethanoic acid, functional group is —COOH (Caboxylic group)
(b) Take few drops of ethanoic acid in a test tube and add sodium hydrogen carbonate solution to it. Brisk effervescence of CO₂ gas is formed which turns lime water milky.
(c) CO₂ gas is evolved. To identify the gas, pass it through freshly prepared limewater, it turns milky due to the formation of milky white precipitate of CaCO₃.
Ca(OH)₂ + CO₂ → CaCO₃ + H₂O

Question 5.
Give reason for the following observations:
(a) The element carbon forms a very large number of compounds.
(b) Air holes of a gas burner have to be adjusted when the heated vessels get blackened by the flame.
(c) Use of synthetic detergents causes pollution of water.  (CBSE 2009)
Answer:
(a) Carbon forms large number of compounds due to its property of catenation,
i.e. self linking. They form isomeric compounds i.e. compounds with same molecular formula but different structural formula.
(b) The vessels blacken due to deposits of black carbon particles on it which is caused due to incomplete combustion of fuel. Air holes are adjusted so that air enters through the holes and helps in complete combustion of the fuel.
(c) Synthetic detergent is non-biodegradable, it remains in the water thereby causing water pollution.

Question 6.
(a) What is a ‘homologous series’ of substances?
(b) In an organic compound, which part largely determine its physical and chemical properties?
(c) Write a chemical equation to represent the reaction of ethanol with acidified
solution of potassium dichromate. (AI 2009)
Answer:
(a) Homologous series is a series of organic compounds having same general formula, all members of the compounds show same chemical properties and slight variation in physical properties.
(b) Functional group.

Question 7.
(a) What is vinegar?
(b) Describe with a chemical equation, what happens when sodium hydrogen carbonate reacts with ethanoic acid.  (AI 2009)
Answer:
(a) The 5% – 10% aqueous solution of acetic acid is called vinegar.
(b)

Ethanoic acid reacts with sodium bicarbonate to produce brisk effervescence of CO₂ gas and sodium acetate.

Question 8.
(a) Write the names of the functional groups in:

(b) Describe a chemical test to distinguish between ethanol and ethanoic acid.
(c) Write a chemical equation to represent what happens when hydrogen gas is passed through an unsaturated hydrocarbon in the presence of nickel as a catalyst.   (Foreign 2009)
Answer:
(a) (i) Ketone
(ii) Aldehyde
(b) On adding Na₂CO₃/NaHCO₃, the test tube containing ethanoic acid produces brisk effervescence of CO₂ gas. Alcohol will not show any reaction.
CH₃COOH + NaHCO₃ → CH₃COONa + CO₂ + H₂O
C₂H₅OH + NaHCO₃ → No reaction

Question 9.
What is an ‘esterification’ reaction? Describe an activity to show esterification.   (CBSE 2011)
Answer:
When carboxylic acid reacts with alcohol in the presence of cone. H₂SO₄, pleasant fruity smelling compound, ester is formed. This reaction is called esterification.

Activity:
(i) Take 1 ml of ethanol in a test tube. Add 1 ml of acetic acid in this test tube.

(ii) Add few drops of conc. H₂SO₄ in the mixture
(iii) Heat the content on water bath for 5 minutes.
(iv) Smell the resulting mixture formed.

Question 10.
Out of HCl and CH₃COOH, which one is a weak acid and why? Describe an activity to support your answer.   (CBSE 2011)
Answer:
Acetic acid (CH₃COOH) is a weaker acid because it does not dissociate completely into its ions in aqueous solution.

Activity:
Add zinc metal in HCl and CH₃COOH taken in different test tubes. The hydrogen gas will be evolved faster in HCl and slowly in CH₃COOH. It shows acetic acid is a weak acid.

Alternative Method:
If we use pH paper, the colour of pH paper will be dark red in HCl and light red in CH₃COOH which shows HCl is a strong acid and CH₃COOH is a weak acid.

Question 11.
Write chemical equations for what happens when
(i) sodium metal is added to ethanoic acid.
(ii) solid sodium carbonate is added to ethanoic acid.
(iii) ethanoic acid reacts with a dilute solution of sodium hydroxide.   (CBSE 2011)
Answer:
(i) H₂ gas is evolved.

(ii) Brisk effervescence due to carbon dioxide gas is formed.

(iii) Sodium ethanoate and water are formed.

Question 12.
Describe two examples of different oxidations of ethanol. Name the products obtained in each case.   (CBSE 2011)
Answer:
(i) When ethanol is heated with copper at 573 K, ethanal is formed.

(ii) When ethanol is oxidised with alkaline potassium permanganate solution, ethanoic acid is formed

Question 13.
Write a chemical equation in each case to represent the following types of chemical reactions of organic compounds:
(i) Oxidation reactions
(ii) Addition reactions
(iii) Substitution reactions.   (CBSE 2011)
Answer:
(i) Oxidation reaction:

(ii) Addition reaction:

(iii) Substitution reaction:

Question 14.
What are isomers? Draw the structures of two isomers of butane, C₄H₁₀. Why can’t we have isomers of first three members of alkane series?  (CBSE 2012)
Answer:
Those compounds, which have same molecular formula but different structural fomulae are called isomers.

In first three members of alkane series, branching is not possible. Therefore, we cannot have isomers.

Question 15.
Define homologous series of organic compounds. List its two characteristics. Write the name and formula of the first member of the series of alkenes.   (CBSE 2012)
Answer:
The series of organic compounds having same functional group and similar chemical properties is called homologous series.
Each member differs from successive member by -CH2- group. The difference in molecular weight between two successive members is 14 u.

Characteristics:

• It has same general formula, from which, all members can be derived.
• They have similar chemical properties.
  C₂H₄, CH₂=CH₂, Ethene is first member of alkene series.

Question 16.
Complete the following equations:
(i) CH₄ + O₂ →

(iii) CH₃COOH + NaOH →     (CBSE 2012)
Answer:
(i) CH₄ + 2O₂ → CO₂(g) + 2H₂O(l)

(iii) CH₃COOH + NaOH → CH₃COONa + H₂O

Question 17.
Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their
(i) physical properties, and
(ii) chemical properties.      (CBSE 2012)
Answer:
The series consists of members of same family with similar chemical properties therefore, called homologous series.
CH₃OH, and CH₃CH₂OH are two consecutive members of homologous series of alcohols.
Alkyl group – CH₃ and – CH₂CH₃ part determines physical properties. Functional group – OH determines chemical properties of the compounds.

Question 18.
Name the oxidising agent used for the conversion of ethanol to ethanoic acid. Distinguish between ethanol and ethanoic acid on the basis of
(i) litmus test,
(ii) reaction with sodium hydrogen carbonate.   (CBSE 2012)
Answer:
Alkaline potassium permanganate or Acidified potassium dichromate.
(i) Ethanol will not affect litmus paper. Ethanoic acid turn blue litmus paper red.
(ii) Ethanol will not react with sodium hydrogen carbonate. Ethanoic acid will give brisk effervescence due to colourless, odourless carbon dioxide gas.

Question 19.
Distinguish between esterification and saponification reactions of organic compounds with the help of the chemical equation for each. What is the use of
(i) esters and
(ii) saponification process?   (CBSE 2012)
Answer:
Esterification: It is a process in which alcohol and carboxylic acid combine in the presence of cone. H₂SO₄ to form ester.

Saponification: When an ester reacts with sodium hydroxide, sodium salt of acid and alcohol is formed.

Uses:
(i) Esters are used as perfumes and as artificial flavouring agents in cold drinks and ice creams.
(ii) Saponification process is used in the manufacture of soaps.

Question 20.
What is meant by functional group in carbon compounds ? Write in tabular form the structural formula and the functional group present in the following compounds : (Foreign 2015)
(i) Ethanol
(ii) Ethanoic acid
Answer:
An atom or a group of atoms/heteroatoms which determine the chemical properties of an organic compound.

Question 21.
With the help of an example, explain the process of hydrogenation. Mention the essential conditions for the reaction and state the change in physical property with the formation of the product.   (Delhi 2015)
Answer:

Addition of hydrogen to the molecule of an unsaturated hydrocarbon/compounds is hydrogenation. Essential condition for hydrogenation is the presence of a catalyst like Ni/Pd/Pt.

Change observed in the physical property during hydrogenation is the change of the unsaturated compound from the liquid state to the corresponding saturated compound in the solid-state and its boiling or melting point will increase.

Question 22.
What is the difference between the molecules of soaps and detergents, chemically? Explain the cleansing action of soaps.   (Delhi 2015)
Answer:
Soaps are sodium or potassium salts of long chain carboxylic acids.
Detergents are ammonium or sulphonate salts.

Soap molecule has two ends, the charged end that gets attracted towards water is called hydrophilic and the long carbon chain that repels water is called hydrophobic tail. When soap is dissolved in water, the carbon chain i.e., hydrophobic end gets attracted towards the oil, dirt and grease. The hydrophilic end stays away from this. The micelle formation takes place.

The tail entangles dirt, oil or grease, if required, the agitation is done. Lot of rinsing is done with water so that water molecules attract charged (Na+) end and carries the soap molecules with dirt attached to it and clean the clothes, utensils, etc.

Question 23.
Explain why carbon forms compounds mainly by covalent bond. Explain in brief two main reasons for carbon forming a large number of compounds. Why does carbon form strong bonds with most other elements?   (Delhi 2015)
Answer:
Carbon has 4 electrons in its outermost shell, and needs to gain or lose 4 electrons to attain noble gas configuration.
Losing or gaining 4 electrons is not possible due to energy considerations; hence it shares electrons to form covalent bonds.

Two reasons for large number of carbon compounds :
Catenation: The unique ability of carbon to form bonds with other atoms of carbon giving rise to long chains of different types of compounds.

Tetravalency : Since carbon has a valency of 4, it is capable of bonding with four other atoms of carbon or atoms of elements like oxygen, hydrogen, nitrogen, sulphur, chlorine, etc.

The reason for the formation of strong bonds by carbon is its small size which enables the nucleus to hold on to the shared pairs of electrons strongly.

Question 24.
Write the molecular formula of the following compounds and draw their electron-dot structures : (Foreign 2015)
(i) Ethane
(ii) Ethene
(iii) Ethyne
Answer:

Question 25.
List two tests for experimentally distinguishing between an alcohol and a carboxylic acid and describe how these tests are performed.  (AI 2015)
Answer:
(a) Acid test: Reaction with carbonates/hydrogen carbonates.
Take samples of alcohol and carboxylic acid in 2 test tubes, and add sodium carbonate or sodium bicarbonate solution to each. The compound which will produce brisk effervescence of CO₂ gas will be acid.

(b) Alcohol test: Take small amount of ethanol and ethanoic acid in test tube A and B. Add 5% solution of alkaline potassium permanganate drop by drop to this solution and warm the test tube.
The colour of potassium permanganate will disappear in test tube containing alcohol.

Question 26.
Draw the electron-dot structure for ethyne. A mixture of ethyne and oxygen is burnt for welding. In your opinion, why cannot we use a mixture of ethyne and air for this purpose?  (AI 2015)
Answer:

In pure oxygen, ethyne undergoes complete combustion and high temperature suitable for welding is attained. Whereas air contains less percentage /amount of oxygen which results in incomplete combustion of ethyne and the temperature required for welding is not attained.

Question 27.
An aldehyde as well as a ketone can be represented by the same molecular formula, say C₃H₆O. Write their structures and name them. State the relation between the two in the language of science.  (AI 2016)
Answer:

Isomers (same molecular formula but different structural formula/different functional group).

Question 28.
What are covalent compounds? Why are they different from ionic compounds? List their three characteristic properties. (Delhi 2016)
Answer:
Covalent compounds are those compounds which are formed by sharing of electrons between two atoms which contain covalent bonds.
Covalent compounds are different from ionic compounds because the ionic compounds are formed by the transfer of electrons.

Three characteristics of covalent compounds:

1. Generally have low melting and boiling points.
2. Generally insoluble or less soluble in water but soluble in organic solvents.
3. Do not conduct electricity. (Or any other characteristic)

Question 29.
When ethanol reacts with ethanoic acid in the presence of cone. H2SO4, a substance with fruity smell is produced. Answer the following:  (Delhi 2016)
Answer:
(i) State the class of compounds to which the fruity smelling compounds belong. Write the chemical equation for the reaction and write the chemical name of the product formed.
(ii) State the role of conc. H₂SO₄ in this reaction.
Answer:
(i) Esters
Chemical equation:

Product’s chemical name – Ethyl ethanoate

(ii) Conc. H₂SO₄ acts as a dehydrating agent (Helps in the removal of water formed in the reaction).

Question 30.
Write the name and molecular formula of an organic compound having its name suffixed with ‘ol’ and having two carbon atoms in its molecule. Write balanced chemical equation to indicate what happens when this compound is heated with excess cone. H₂SO₄ and the name of main product formed. Also state the role of conc. H₂SO₄ in the reaction.   (Foreign 2016)
Answer:
Ethanol; C₂H₅OH / C₂H₆O

Role of conc. H₂SO₄ – dehydrating agent.

Question 31.
An organic compound ‘P’ is a constituent of wine. ‘P’ on reacting with acidified K₂Cr₂O₇ forms another compound ‘Q’. When a piece of sodium is added to ‘Q’ a gas ‘R’ evolves which burns with a pop sound. Identify P, Q and R and write the chemical equations of the reactions involved.   (Foreign 2016)
Answer:
P – Ethanol, Q – Ethanoic acid, R – Hydrogen

Question 32.
Write chemical equation of the reaction of ethanoic acid with the following:   (AI 2016)
(a) Sodium;
(b) Sodium hydroxide;
(c) Ethanol
Answer:

Carbon and its Compounds Class 10 Important Questions Long Answer Type

Question 1.
(a) Why does carbon form compounds mainly by covalent bonding?
(b) List any two reasons for carbon forming a very large number of compounds.
(c) An organic acid ‘X’ is a liquid which often freezes during wintertime in cold countries, has the molecular formula, C₂H₄O₂. On warming it with ethanol in the presence of a few drops of concentrated sulphuric acid, a compound Y with a sweet smell is formed.
(i) Identify ‘X’ and ‘Y’.
(ii) Write a chemical equation for the reaction involved.   (CBSE 2008)
Answer:
(a) Carbon forms compounds mainly by covalent bonding because carbon has small size, so neither it can lose four electrons easily, because very high amount of energy will be required, nor it can gain four electrons as 6 parotons cannot hold 10 electrons. Hence, it shares four electrons forming covalent bonds.

(b) (i) Due to catenation – Self linking property
(ii) Tetravalency of carbon – Forms compounds with other elements.

(c) (i) ‘X’ is CH₃COOH, it freezes during winter in cold countries.
‘Y is ester CH₃COOC₂H₅

Question 2.
(a) What is homologous series of compounds? List any two characteristics of a homologous series.
(b) (i) What would be observed on adding 5% solution of alkaline potassium
permanganate solution drop by drop to some warm ethanol taken in a test tube?
(ii) Write the name of the compound formed during the chemical reaction.
(c) How would you distinguish experimentally between an alcohol and a carboxylic acid on the basis of a chemical property?   (CBSE 2008)
Answer:
(a) Organic compounds when arranged in series having same general formula and similar chemical properties is called homologous series.

Two characteristics of homologous series.

1. Each successive member differ by – CH₂ group, 14 u.
2. The method of preparation and chemical properties of members of homologous
   series is same.

(b) (i) The colour of KMnO₄ will get discharged because ethanol gets oxidised to
form ethanoic acid.
\(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}+2(\mathrm{O}) \stackrel{\text { alk. } \mathrm{KMnO}_{4}}{\longrightarrow} \mathrm{CH}_{3} \mathrm{COOH}+\mathrm{H}_{2} \mathrm{O}\)
(ii) Ethanoic acid, CH₃COOH

(c) On adding sodium bicarbonate solution to both the test tubes containing ethanol and ethanoic acid the test tube containing carboxylic acid (ethanoic acid) will show brisk effervescence due to formation of CO₂ gas. Alcohol will not react with sodium bicarbonate.

Question 3.
(a) What is a functional group in a carbon compound?. Identify the functional group present in CH₃COOH and C₂H₅OH.
(b) State the principle on which the cleansing action of soap is based. (Foreign 2008)
Answer:
(a) The atom or group of atoms which determines the properties of a compound is called functional group.
C₂H₂OH has (- OH) alcoholic group
CH₃COOH has (- COOH) carboxylic functional group

(b) Cleansing action of soap depends on its structure, it has two ends hydrophobic which attracts dirt, oil or grease and hydrophilic end which attracts water.

The dirt is carried by hydrophobic portion which is attached to hydrophilic end which gets attached to water and is washed away.

Question 4.
(a) What is homologous series? Give one example.
(b) What will happens if ethanoic acid reacts with ethanol in the presence of an acid as a catalyst? Name the reaction. Write the chemical reaction for this reaction.
(c) Why are soaps ineffective in hard water?  (CBSE 2008C)
Answer:
(a) Homologous series is series of compounds having same functional group and same chemical properties. When members of the series are arranged in ascending order, two successive members differ by -CH2 group and mass 14 u.
Example:

(b) Ethanol reacts with ethanoic acid to produce a fruity smelling compound called ester, the cone, sulphuric acid is used as dehydrating agent which removes water. Such reaction is called esterification.

(c) Hard water contains salts of Ca and Mg. Soap molecule reacts with these salts to produce white precipitate called scum, which is insoluble in water and the cleansing action of soap becomes ineffective.

Question 5.
(a) The structural formula of an easter is

Write the structural formula of the corresponding alcohol and the acid.
(a) (i) Mention the experimental conditions involved in obtaining ethene from ethanol.
(ii) Write the chemical equation for the above reaction.
Explain the cleansing action of soap.   (Foreign 2009)
Answer:
(a) CH₃COOH and CH₃CH₂OH
(b) (i) Ethanol when heated in presence of cone. H₂SO₄, it gets dehydrated to form ethene at 160°C – 170°C.

Question 6.
(a) Distinguish between esterification and saponification reactions of organic compounds.
(b) With a labelled diagram describe an activity to show the formation of an ester.  (AI 2009)
Answer:
Esterification: Reaction in which carboxylic acid reacts with alcohol in presence of cone. H₂SO₄ to form a fruity smelling compound called ester.

Saponification: It is a reaction in which an ester reacts with alkali solution to form a compound called soap.

(b) Activity to show the formation of an ester: Take a test tube and add ethanol, acetic acid and few drops of cone. H₂SO₄ in it. Warm it over a water bath, i.e., keeping the test tube in a beaker containing water. Pleasant, fruity smelling compound called ester is formed.

Question 7.
(a) State two properties of carbon which lead to a very large number of carbon compounds.
(b) Why does micelles formation take place when soap is added to water? Why are micelles not formed when soap is added to ethanol?   (CBSE 2011)
Answer:
(a) (i) Catenation
(ii) Tetravalency

(b) Soap has hydrophobic tail (hydrocarbon) which attracts towards oil or dirt and hydrophilic part dissolves in water. When large number of molecular ions of soaps get aggregated then to keep hydrophic tail away from water and closer to oil there tails of molecules point at the centre of a sphere and hydrophilic part at the surface of sphere which causes the micelle formation.

Micelles are not formed in ethanol because hydrocarbon part gets dissolved in ethanol thus, it does not suspend around oil particles. Hence, micelles are not formed in ethanol.

Question 8.
Explain isomerism. State any four characteristics of isomers. Draw the structures of possible isomers of butane, C₄H₁₀.   (CBSE 2011)
Answer:
Isomerism is a phenomenon due to which some compounds have same molecular formula but different structural fomulae.

Characteristics:

• They differ in structural formula
• They differ in melting point
• They differ in boiling point.
• They differ in solubility in same solvent.

Question 9.
There are two isomers of butane, C₄H₁₀.

Give reasons for the following:
(i) Element carbon forms compounds mainly by covalent bonding.
(ii) Diamond has a high melting point.
(iii) Graphite is a good conductor of electricity.
(iv) Acetylene burns with a sooty flame.
(v) Kerosene does not decolourise bromine water while cooking oils do.  (CBSE 2011)
Answer:
(i) It is because carbon has four valence electrons, it cannot gain or lose four electrons because high energy is needed. It can only share four electrons.
(ii) It is due to strong covalent bonds and compact structure of diamond.
(iii) It is due to presence of free electrons in graphite because each carbon is linked to three other carbon atoms.
(iv) It is due to high percentage of carbon, it burns with sooty or smoky flame.
(v) Kerosene oil is mixture of saturated hydrocarbons while cooking oils are unsaturated hydrocarbons therefore bromine undergoes addition reaction with cooking oils and gets decolourised.

Question 10.
List in tabular form three physical and two chemical properties on the basis of which ethanol and ethanoic acid can be differentiated.   (CBSE 2012)
Answer:
Physical properties:

Ethanol	Ethanoic acid
1. It has specific smell	1. It has vinegar like smell.
2. It has burning taste	2. It is sour in taste
3. It does not freeze in winters	3. It freezes in winters

Chemical properties:

Ethanol	Ethanoic acid
1. It does not react with NaHCO3	1. It gives CO2 with NaHCO3
2. It burns with blue flame	2. It does not bum with blue flame
3. It does not affect blue litmus	3. It turns blue litmus red

Question 11.
What are the hydrocarbons? Write the name and general formula of (i) saturated hydrocarbons, (ii) unsaturated hydrocarbons, and draw the structure of one hydrocarbon of each type. How can an unsaturated hydrocarbon be made saturated?   (CBSE 2012)
Answer:
Hydrocarbons are the compounds of carbon and hydrogen.
(i) Alkanes, C_nH_2n+2 are saturated hydrocarbons.

(ii) Alkenes, C_nH_2n and Alkynes, C_nH_2n-2 are unsaturated hydrocarbons.

Unsaturated hydrocarbons can be made saturated by hydrogenation.

Question 12.
What are detergents chemically? List two merits and two demerits of using detergents for cleansing. State the reason for the suitability of detergents for washing, even in the case of water having calcium and magnesium ions. (CBSE 2012)
Answer:
Detergents chemically are ammonium or sulphonate salts with long carbon chain
Merits:

1. They work well with hard water.
2. They are more effective than soaps.

Demerits:

1. They are expensive.
2. Some of them having branching and are non-biodegradable, therefore create water pollution.
   Detergents are suitable for hard water having Mg²⁺ and Ca²⁺ ions because they do not form insoluble salts with Mg²⁺ and Ca²⁺ ions.

Question 13.
Both soap and detergent are some type of salts. What is the difference between them? Describe in brief the cleansing action of soap. Why do soaps not form lather in hard water? List two problems that arise due to the use of detergents instead of soaps.  (AI 2015)
Answer:
Soaps are sodium or potassium salts of long chain carboxylic acids.
Detergents are ammonium or sulphonate salts with long carbon chain.

Cleansing action of soap:
Soap molecule has two ends, the charged end that gets attracted towards water is called hydrophilic and the long carbon chain that repels water is called hydrophobic tail. When soap is dissolved in water, the carbon chain i.e., hydrophobic end gets attracted towards the oil, dirt and grease. The hydrophilic end stays away from this. The micelle formation takes place.

The tail entangles dirt, oil or grease, if required, the agitation is done. Lot of rinsing is done with water so that water molecules attract charged (Na+) end and carries the soap molecules with dirt attached to it and clean the clothes, utensils, etc.

Problems due to the use of detergents are:

• Detergents are non-biodegradable
• It leads to water or soil pollution.
• It can also cause skin problems.

Question 14.
Elements forming ionic compounds attain noble gas electronic configuration by either gaining or losing electrons from their valence shells. Explain giving reason why carbon cannot attain such a configuration in this manner to form its compounds. Name the type of bonds formed in ionic compounds and in the compounds formed by carbon. Also explain with reason why carbon compounds are generally poor conductors of electricity.  (Foreign 2015)
Answer:
Carbon has 4 electrons in its outermost shell. It cannot lose 4 electrons to form C⁴⁺ because very high energy is required to remove 4 electrons.
It cannot gain 4 electrons to form C^4- ions because it is difficult for 6 protons to hold on to 10 electrons.

Ionic/Electrovalent bonds are formed in ionic compounds. Covalent bonds are formed in carbon compounds. There are no free electron or charged particle in carbon compound hence they are poor conductors of electricity.

Question 15.
(a) Give a chemical test to distinguish between saturated and unsaturated hydrocarbon.
(b) Name the products formed when ethane burns in air. Write the balanced chemical equation for the reaction showing the types of energies liberated.
(c) Why is reaction between methane and chlorine in the presence of sunlight considered a substitution reaction?   (Delhi 2016)
Answer:
(a) Pass the vapours of the given samples of saturated and unsaturated hydrocarbons into bromine water taken in two separate test tubes. The one which discharges the colour of bromine water is that of unsaturated hydrocarbon and the other represents saturated hydrocarbon (or any other test).

(b) On burning ethane in air, the products obtained are carbon dioxide and water, along with heat and light.
2C₂H₆(g) + 7O₂(g) → 4CO₂(g) + 6H₂O(l) + Heat + Light

(c) It is considered a substitution reaction because the hydrogen atoms of methane (CH₄) are replaced by chlorine atoms one by one.

Question 16.
(a) You have three unlabelled test tubes containing ethanol, ethanoic acid and soap solution. Explain the method you would use to identify the compounds in different test tubes by chemical tests using litmus paper and sodium metal.
(b) Give the reason for formation of scum when soaps are used with hard water.  (Foreign 2016)
Answer:
(a)

Solution	Blue Litmus Paper	Red Litmus Paper	Sodium Metal
Ethanol	No change	No change	Hydrogen gas
Ethanoic Acid	Turns red	No change	Hydrogen gas
Soap	No change	Turns blue	Hydrogen gas

(b) Hard water contains calcium ions or magnesium ions or both. These ions on reacting with soap solution forms insoluble substance called scum.

Question 17.
A carbon compound ‘P’ on heating with excess cone. H₂SO₄ forms another carbon compound ‘Q’ which on addition of hydrogen in the presence of nickel catalyst forms a saturated carbon compound ‘R’. One molecule of ‘R’ on combustion forms two molecules of carbon dioxide and three molecules of water. Identify P, Q and R and write chemical equations for the reactions involved.  (AI 2016)
Answer:
P = Ethanol / C₂H₅OH
Q = Ethene / CH₂=CH₂
R = Ethane / C₂H₆

Solved the very best collection of Metals and Non-metals Class 10 Science Important Questions and Answers Chapter 3 Pdf from the latest NCERT edition books, It will help you in scoring more marks in CBSE Exams.

Metals and Non-metals Class 10 Important Questions with Answers Science Chapter 3

Metals and Non-metals Class 10 Important Questions Very Short Answer Type

Question 1.
Name a reducing agent that may be used to obtain manganese from manganese dioxide.   (CBSE 2009)
Answer:
Aluminium.

Question 2.
A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.   (CBSE 2011)
Answer:
‘X’ is carbon, Y is diamond as it is the hardest natural substance and ‘Z’ is graphite as it is a good conductor of electricity.

Question 3.
Why does calcium float on water?   (CBSE 2011)
Answer:
When calcium is added to water it quickly reacts with it to release hydrogen gas. The bubbles of the hydrogen gas sticks to the surface of calcium and makes it float on water.

Question 4.
Name a non-metal which is lustrous and a metal which is non-lustrous.  (CBSE 2011)
Answer:
Non-metal: Iodine is lustrous and Metal: Lead is non lustrous.

Question 5.
Which gas is liberated when a metal reacts with an acid? How will you test the presence of this gas?   (CBSE 2011)
Answer:
Hydrogen gas is formed. Bring a burning matchstick near to it, H₂ will burn explosively with ‘pop’ sound.

Question 6.
Name the metal which reacts with a very dilute HNOs to evolve hydrogen gas.   (CBSE 2011)
Answer:
Magnesium

Question 7.
Name two metals which are found in nature in the free state.   (CBSE 2011)
Answer:

1. Gold
2. Platinum.

Question 8.
A green layer is gradually formed on a copper plate left exposed to air for a week in a bathroom. What could this green substance be?    (CBSE 2012)
Answer:
It is due to the formation of basic copper carbonate [CuCO₃]

Metals and Non-metals Class 10 Important Questions Short Answer Type

Question 1.
From amongst the metals sodium, calcium, aluminium, copper and magnesium, name the metal
(i) which reacts with water only on boiling and
(ii) another which doesnot react even with stream.   (CBSE 2008)
Answer:
(i) Magnesium reacts with water only on boiling
(ii) copper metal doesnot react even with stream

Question 2.
(a) Show the formation of Nacl from sodium and chlorine atoms by the transfer of electrons?
(b) why sodium chloride has a high melting point?
(c) Name the anode and cathode used in electrolytic refining of impure copper metal. (CBSE 2008)
Answer:

(b) Due to strong force of attraction between Na⁺ and Cl^–, sodium chloride has high melting point.
(c) Impure copper acts as anode, pure copper acts as cathode.

Question 3.
(a) Show the formation of Na₂O by the transfer of electrons between the combining atoms.
(b) Why are ionic compounds usually hared?
(c) How is it that ionic compounds in the solid state do not conduct electricity but they do so when in molton state  (CBSE 2008)
Answer:

(b) Ionic compounds are hard due to strong force of attraction between oppositely charged ions.
(c) In solid state, ions are not free to move where as molton state, ions are free to move, there fore they conduct electricity in molton state.

Question 4.
On adding dilute HCl acid to copper oxide powder, the solution formed is blue-green. Predict the new compound formed which imparts a blue-green colour to the solution.   (CBSE 2008)
Answer:
The name of the compound is cupric chloride which gives blue-green colour to the solution.
CuO + 2HCl → CuCl₂ + H₂O

Question 5.
(a) Show on a diagram the transfer of electrons between the atoms in the formation of MgO.
(b) Name the solvent in which ionic compounds are generally soluble.
(c) Why are aqueous solutions of ionic compounds able to conduct electricity? (CBSE 2008)
Answer:

(b) Ionic compounds are soluble in water.
(c) The aqueous solutions of ionic compounds consist of ions which can move freely and conduct electricity.

Question 6.
(a) What are amphoteric oxides? Choose the amphoteric oxides from amongst the following oxides?
Na₂O, ZnO, Al₂O₃, CO₂, H₂O.
(b) Why is it that non-metals do not displace hydrogen from dilute acids?   (AI 2008)
Answer:
(a) The oxides which are acidic as well as basic in nature are called amphoteric oxides. Al₂O₃ and ZnO are amphoteric oxides.
(b) Non-metals cannot lose electrons so that H⁺ ions from acids become hydrogen gas and can be displaced.

Question 7.
Name two metals which react violently with cold water. Write any three observations you would make when such a metal is dropped into water. How would you identify the gas evolved, if any during the reaction?   (AI 2008)
Answer:
Sodium and potassium react vigorously with cold water.
When these metals are dropped in water, bubbles will be evolved due to evolution of hydrogen gas, large amount of heat is produced and the solution will change red litmus blue.

Hydrogen gas is formed. Bring burning splinter near the mouth of the test tube where gas is evolved, the splinter burns with a pop sound.

Question 8.
(a) Name a metal for each case
(i) it does not react with cold as well as hot water but reacts with steam.
(ii) it does not react with any physical state of water.
(b) When calcium metal is added to water the gas evolved does not catch fire, on adding sodium metal to water catches fire. Why is it so?   (AI 2008)
Answer:
(a) (i) Iron metal reacts only with steam.
(ii) Copper does not react with any state of water.
(b) Sodium metal is highly reactive. It reacts with water and produces sodium hydroxide and hydrogen gas along with large amount of heat. Due to this large heat, hydrogen catches fire while no such huge amount of heat is released in case of calcium.

Question 9.
Show the electronic transfers in the formation of MgCl₂ from its elements.    (Foreign 2008)
Answer:

Question 10.
Which of the following metals will melt at body temperature (37°C)?    (CBSE 2008C)
gallium, magnesium, caesium, aluminium.
Answer:
Gallium and caesium.

Question 11.
Give reasons for the following:
(a) Gold and silver are used to make jewellery.
(b) Carbonate and sulphide ores are usually converted into oxides prior to reduction
during the process of extraction.    (CBSE 2008C)
Answer:
(a) It is because gold and silver are highly lustrous, malleable and ductile.
(b) The reduction of metal oxides into metals is easy, fast and cheap than converting carbonate and sulphide ore into metals.

Question 12.
Give reasons for the following:
(a) Metals can be given different shapes according to our needs.
(b) Hydrogen is not evolved when a metal reacts with nitric acid.
Answer:
(a) Metals are malleable and ductile i.e. it can be drawn into sheets and wires, it does not break due to high tensile strength and therefore it can be given different shapes according to our needs.
(b) Nitric acid is strong oxidising agent. When metals react with nitric acid it does
not release H₂ gas but oxidise it to form H₂O.

Question 13.
Give reasons for the following:     (CBSE 2008C, 2012)
(a) Aluminium oxide is considered as an amphoteric oxide.
(b) Ionic compounds conduct electricity in molten state.
Answer:
(a) Aluminium oxide reacts with acids as well as bases to form salt. It shows the properties of both acid and base.
(b) Ionic compounds produce free ions in molten state which conduct electricity.

Question 14.
The way, metals like sodium, magnesium and iron react with air and water is an indication of their relative positions in the ‘reactivity series’. Is this statement true? Justify your answer with examples.    (CBSE 2011)
Answer:
The arrangement of metals in the reactivity series is based on the property of their reactivity i.e., how quickly they react in same conditions. The most reactive metal is placed on the top and the least one at the bottom of the series. Sodium will quickly react with water, and magnesium will react slowly and iron metal will take many hours to react. Hence sodium is placed at the top and iron at the bottom based on their ractivity pattern.

Question 15.
X + YSO₄ → XSO₄ + Y
Y + XSO₄ → No reaction
Out of the two elements, ‘X’ and ‘Y, which is more reactive and why?   (CBSE 2011)
Answer:
‘X’ is more reactive than ‘Y because it displaces ‘Y from its salt solution.

Question 16.
What is an alloy? State the constituents of solder. Which property of solder makes it suitable for welding electrical wires?     (CBSE 2011)
Answer:
Alloy is a homogeneous mixture of two or more metals. One of them can be a non-metal also. Solder consists of lead and tin. It has low melting point which makes it suitable for welding electrical wires.

Question 17.
Using the electronic configurations, explain how magnesium atom combines with oxygen
atom to form magnesium oxide by transfer of electrons.    (CBSE 2011)
Answer:

Question 18.
When a metal X is treated with cold water, it gives a base Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z.    (CBSE 2011)
Answer:
2Na + 2H₂O → 2NaOH + H₂
Here ‘X’ is Sodium metal, ‘Y is sodium hydroxide and ‘Z’ is Hydrogen gas.

Question 19.
Write chemical equations that shows aluminium oxide reacts with acid as well as base.
(CBSE 2011)
Answer:
Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O

Question 20.
Name the following:
(a) A metal, which is preserved in Kerosene.
(b) A lustrous coloured non-metal.
(c) A metal, which can melt while kept on palm.
(d) A metal, which is a poor conductor of heat.    (CBSE 2012)
Answer:
(a) Sodium is preserved in Kerosine.
(b) Iodine is lustrous non-metal.
(c) Gallium.
(d) Lead.

Question 21.
Explain the formation of ionic compound CaO with electron number of calcium and oxygen are 20 and 8 respectively.
(b) Name the constituent metals of bronze.    (CBSE 2012)
Answer:

(b) Bronze is made up of copper and tin.

Question 22.
A metal ‘X’ acquires a green colour coating on its surface on exposure to air.
(i) Identify the metal ‘X’ and name the process responsible for this change.
(ii) Name and write chemical formula of the green coating formed on the metal.
(iii) List two important methods to prevent the process.     (CBSE 2012)
Answer:
(i) Metal is copper. The process is corrosion.
(ii) Copper carbonate [CuCO₃].
(iii) (a)It should be coated with zinc
(b) It should be mixed with other metals to form alloys.

Question 23.
Write balanced equations for the reaction of:
(i) aluminium when heated in air. Write the name of the product.
(ii) iron with steam. Name the product obtained.
(iii) calcium with water. Why does calcium start floating in water?   (CBSE 2012)
Answer:
(i) \(4 \mathrm{Al}+3 \mathrm{O}_{2} \stackrel{\text { heat }}{\longrightarrow} 2 \mathrm{Al}_{2} \mathrm{O}_{3}\)
The product formed is aluminium oxide.
(ii) 3Fe + 4H₂O (steam) → Fe₃O₄ + 4H₂
The product obtained is iron (II) iron (III) oxide.
(iii) Ca + 2H₂O → Ca(OH)₂ + H₂
The bubbles of hydrogen stick to the surface of metal which when moves up takes metal with it and makes it float.

Question 24.
Write balanced chemical equations for the following reactions:
(a) Dilute sulphuric acid reacts with aluminium powder.
(b) Dilute hydrochloric acid reacts with sodium carbonate.
(c) Carbon dioxide is passed through lime water. (CBSE 2012)
Answer:
(a) 2Al(s) + 3H₂SO₄(dil.) → Al₂(SO₄)₃(aq) + 3H₂(g)
(b) Na₂CO₃(s) + 2HCl(dil.) → 2NaCl(aq) + H₂O(l) + CO₂(g)
(c) Ca(OH)₂(aq) + CO₂(g) → CaCO₃(s) + H₂O(l)

Question 25.
(a) Show the formation of Na₂O by the transfer of electrons between the combining atoms.
(b) Why are ionic compounds usually hard?
(c) How is it that ionic compounds in the solid state do not conduct electricity but
they do so when in molten state?   (CBSE 2012)
Answer:

(b) It is due to strong force of attraction between oppositely charged ions.
(c) In solid-state, ions are not free to move whereas in molten state ions are free to move, therefore, they conduct electricity in molten state.

Question 26.
(a) Show on a diagram the transfer of electrons between the atoms in the formation of MgO. Write symbols of cation and anion present in MgO.
(b) Name the solvent in which ionic compounds are generally soluble.
(c) Why are aqueous solutions of ionic compounds able to conduct electricity?    (CBSE 2012)
Answer:

MgO contains Mg²⁺ as cation and O^2- as anion.
(b) Ionic compounds are soluble in water.
(c) It is because aqueous solutions consist of ions which can move freely and carry current.

Question 27.
Define the following terms:    (CBSE 2012)
(i) Mineral
(ii) Ore
(iii) Gangue
Answer:
(i) Mineral: The naturally occurring chemical substance which contains metals with some other elements or impurities is called mineral.
(ii) Ore: The minerals from which metals can be extracted economically on large scale are called ores.
(iii) Gangue: The impurities present in ore/minerals are called gangue.

Question 28.
Give reason for the following:   (CBSE 2013)
(a) School bells are made up of metals.
(b) Electric wires are made up of copper.
Answer:
(a) It is because metals are sonorous, i.e., they produce sound when struck with a hard substance.
(b) It is because copper is good conductor of electricity and economical.

Question 29.
Suggest a method of reduction for the following metals during their metallurgical processes:   (CBSE 2013)
(i) metal ‘A’ which is one of the last, second or third position in the reactivity.
(ii) metal ‘B’ which gives vigorous reaction even with water and air.
(iii) metal ‘C’ which is kept in the middle of activity series.
Answer:
(i) A can be obtained by chemical reduction using carbon or carbon monoxide as reducing agent.
(ii) ‘B’ can be obtained by electrolytic reduction.
(iii) ‘C’ can be reduced by reducing agent like Al.

Question 30.
(a) Define activity series of metals. Arrange the metals gold, copper, iron and magnesium in order of their increase in reactivity.   (CBSE 2013)
(b) What will you observe when:
(i) Some zinc pieces are put in copper sulphate solution.
(ii) Some silver pieces are put into green coloured ferrous sulphate solution.
Answer:
(a) The series of metals in which metals are arranged in decreasing order of their reactivity. Au < Cu < Fe < Mg is increasing order of reactivity.
(b) (i) The blue solution will become colourless and reddish brown copper metal will be deposited.
\(\mathrm{Zn}(\mathrm{s})+\underset{\text { Blue }}{\mathrm{CuSO}_{4}(\mathrm{aq})} \longrightarrow \underset{\text { colourless }}{\mathrm{ZnSO}_{4}(\mathrm{aq})}+\underset{\text { (reddish brown })}{\mathrm{Cu}(\mathrm{s})}\)
(ii) Ag(s) + FeSO₄(aq) → No reaction
Reaction will not take place-because ‘Ag’ is less reactive than iron.

Question 31.
You are given samples of three metals. Sodium, magnesium and copper. Suggest any two activities to arrange them in order of decreasing activity.   (CBSE 2014)
Answer:
Activity: Sodium reacts with cold water vigorously to form sodium hydroxide and hydrogen gas
2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)
Magnesium does not react with cold water but with hot water to form magnesium hydroxide and hydrogen gas.
Mg(s) + 2H₂O(l) → Mg(OH)₂(aq) + H₂(g)
Copper does not react even with steam.
Hence sodium is more reactive than magnesium which is more reactive than copper.

Question 32.
Explain why
(a) iron articles are frequently painted.
(b) iron sheets are coated with zinc layer.   (CBSE 2014)
Answer:
(a) Iron articles when come in contact with oxygen and water (moisture), rust to form flaky substance on its surface and slowly loses its strength. To avoid this it is painted frequently.
(b) Iron sheets are coated with zinc (galvanisation) so as to prevent iron from rusting.

Question 33.
Write one example of each of
(i) a metal which is so soft that, it can be cut with knife and a non-metal which is the hardest sustance.
(ii) a metal and a non-metal which exist as liquid at room temperature.    (CBSE 2015)
Answer:
(i) Sodium, carbon (diamond).
(ii) Mercury is liquid metal, bromine is liquid non-metal.

Question 34.
Mention the names of the metals for the following:    (CBSE 2015)
(i) Two metals which are alloyed with iron to make stainless steel.
(ii) Two metals which are used to make jewellary.
Answer:
(i) Nickel and chromium.
(ii) Gold and platinum.

Question 35.
State three reasons for the following facts
(i) Sulphur is a non-metal
(ii) Magnesium is a metal
One of the reasons must be supported with a chemical equation.   (CBSE 2015)
Answer:

Question 36.
What is cinnabar? How is metal extracted from cinnabar? Explain briefly.   (CBSE 2015)
Answer:
Cinnabar is HgS.
Mercury is obtained by roasting cinnabar. HgO formed is thermally unstable and gives mercury.

Mercury can purified by distillation.

Question 37.
(a) Write the electron dot structures for potassium and chlorine.
(b) Show the formation of KCl by the transfer of electrons.
(c) Name the ions present in the compound KCl.
Answer:

(c) KCl has K⁺ and Cl^–.

Question 38.
(a) State the electron-dot structures for calcium and sulphur.
(b) Show the formation of CaS by the transfer of electrons.
(c) Name the ions present in this compound CaS. Atomic number of Ca = 20, O = 16.   (CBSE 2015)
Answer:

(c) Ca²⁺ and S^2- ions are present in CaS.

Metals and Non-metals Class 10 Important Questions Long Answer Type

Question 1.
Sample pieces of 5 metals A, B, C, D and E are added to the tabulated solutions separately. The results observed are shown in the table.   (Foreign 2008)

Based on the observations recorded in the table, answer the following?
(i) Which is the most reactive metal?
(ii) Which is the least reactive metal?
(iii) What would be observed if metal D were added to a solution of copper (II) sulphate?
(iv) What would be observed if metal E were added to a solution of iron (II) sulphate?
(v) Arrange the metals A, B, C, D and E in order of decreasing reactivity.
Answer:
(i) The most reactive metal is E as it displaces Zn from ZnSO₄ solution.
(ii) The least reactive metal is C as it cannot displace even Ag from AgNO₃.
(iii) If ‘D’ is more reactive than copper, then the brown coating on the metal would be formed.
(iv) ‘E’ is more reactive than Fe, hence it can displace Fe form FeSO₄, a grey coating on metal will be formed.
(v) E > B > D > A > C

Question 2.
(a) With a labelled diagram, describe an activity to show that metals are good conductors of electricity.
(b) Account for the following:
(i) Hydrogen gas is not evolved when a metal reacts with nitric acid.
(ii) For storing, sodium metal is kept immersed in kerosene.
(iii) The reaction of iron (III) oxide, Fe₂O₃ with aluminium is used to join cracked iron parts of machines. (Foreign 2008)
Answer:
(a) Activity: To show that metals are good conductors of electricity.
Materials: Metal pieces, like Zn, Fe, Cu and Al, connecting clips, battery, bulb, and wires.
Set the apparatus as shown in the figure, place different metals between the clips A and B. The bulb glows when all of these metals are placed between the clips.
This proves that metals are good conductors of electricity.

(b) (i) Nitric acid is a strong oxidising agent, it oxidises the H₂ gas to H₂O.
(ii) Sodium is very reactive metal, it reacts with water and oxygen at room temperature, but it does not react with kerosene, so it is stored under kerosene.
(iii) The reaction of aluminium with iron (III) oxide is highly exothermic, it produces iron metal in molten form, which helps in joining the cracked iron parts of a machine.

Question 3.
(a) Describe an activity to find out which metal is more reactive-iron or copper?
(b) Arrange the following metals in decreasing order of their reactivity.
Fe, Zn, Na, Cu, Ag
(c) Why do ionic compounds have high melting points?
(d) Show the formation of NaCl from Na and Cl atoms by the transfer of electrons.   (AI 2008C)
Answer:
(a) To find more reactive metal among iron and copper.
Arrange the following setup:

In test tube A, iron metal when dipped in CuSO₄ it displaces copper from its solution to form iron sulphate and copper metal gets deposited on the surface of iron metal.
In test tube B – No reaction takes place. This shows that iron is more reactive than copper.
(b) Na > Zn > Fe > Cu > Ag
(c) Ionic compounds have high melting point because there are strong forces of attraction between ions due to which large amount of energy is required to break this bond.

Question 4.
(a) Give an example of a metal which
(i) can be easily cut with a knife,
(ii) is a liquid at room temperature.
(b) Write chemical equation for the reaction when
(i) Steam acts on red hot iron.
(ii) Zinc is added to iron (II) sulphate solution.
(c) What are alloys?
(d) Why are food cans coated with tin and not zinc?   (AI 2008C)
Answer:
(a) (i) Sodium can be cut with knife.
(ii) Mercury is liquid at room temperature.
(b) (i) 3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)
(ii) Zn(s) + FeSO₄(aq) → ZnSO₄(aq) + Fe(s)
(c) Alloys are homogeneous mixture of two or more than two metals or metals and non-metals.
(d) Food cans are coated with tin and not zinc. Because tin is less reactive than zinc it does not corrode easily and it is cheaper.

Question 5.
(a) Name the main ore of mercury. How is mercury obtained from its ore? Give balanced chemical equation.
(b) What is thermite reaction? How is it used to join the railway tracks or craked machine parts?
(c) Name the method used to extract metals of high reactivity.   (CBSE 2011)
Answer:
(a) Cinnabar
Mercury is obtained from its ore by roasting.
HgS + O₂ → Hg + SO₂
(b) When aluminium is heated with Fe₂O₃ to get molton iron, it is called thermite reaction.
Fe₂O₃ + 2Al → Al₂O₃ + 2Fe
Molten iron is used to weld broken railway tracks.
(c) Electrolytic reduction.

Question 6.
(a) How can the metals at the top of the reactivity series be extracted from their ores? Explain with an example.
(b) Name any one alloy made from
(i) a metal and a non-metal, and
(ii) two metals.      (CBSE 2011)
Answer:
(a) These metals are extracted by electrolytic reduction, e.g., aluminium is obtained
from bauxite by electrolytic reduction.
(b) (i) Steel is made up of iron and carbon.
(ii) Brass is made up of copper and zinc.

Question 7.
(a) Give two methods to prevent the rusting of iron.
(b) Name the ores of the following metals:
(i) mercury, and
(ii) zinc
(c) Explain with the help of a diagram, how copper metal can be refined? Label the
important arrangements in the experimental setup.   (CBSE 2011)
Answer:
(a) (i) Painting
(ii) Galvanisation
(b) (i) Cinnabar
(ii) Zinc Blende
(c) Impure copper is taken as anode whereas , pure copper is taken as cathode. Copper sulphate solution (CuS04) is taken as electrolyte. When electric current is passed, impure copper changes to ions which gain electrons at cathode and change into pure copper. Impurities are left behind as anode mud.
At anode: Cu(s) → Cu²⁺(aq) + 2e^–
At cathode: Cu²⁺(aq) + 2e^– → Cu(s)

Question 8.
With the help of a suitable example, explain how ionic compounds are formed. State any three general properties of ionic compounds. (CBSE 2011)
Ans. Ionic compounds are formed by transfer of electrons from metal to non-metals, e.g.

General Properties:
(i) They are the solids having high melting point.
(ii) They are soluble in water.
(iii) They conduct electricity in molten state as well as in aqueous solution.

Question 9.
(a) Explain with an example how the metal (X) which is low in reactivity series and metal (Y) which is high in the reactivity series are obtained from their compounds by reduction process.
(b) Write the electronic configuration of sodium and chlorine. Show the formation of sodium chloride from sodium and chlorine by the transfer of electrons.
(c) List any two observations when a highly reactive metal is dropped in water.   (CBSE 2011)
Answer:
(a) ‘X’ is obtained by chemical reduction with the metals high in reactivity series. ‘Y is obtained by electrolytic reduction.

(c) (i) Metal will catch fire.
(ii) Alkali solution is formed which turns red litmus blue.

Question 10.
The reaction of metal (X) with ferric oxide is highly exothermic. Metal (X) is obtained from its oxides by electrolytic reduction. Identify (X) and write its reaction with ferric oxide.
(b) Give reason to justify that aluminium oxide is an amphoteric oxide. Also, give another example of amphoteric oxide.
(c) Mention constituent metals present in bronze.   (CBSE 2011)
Answer:
(a) ‘X’ is ‘Al’
2Al(s) + Fe₂O₃(s) → Al₂O₃(s) + 2Fe(l) + Heat
(b) Al₂O₃ reacts with acid as well as base, therefore it is amphoteric oxide.
Al₂O₃ + 2NaOH → 2NaAlO₃ + H₂O
Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂
Zinc oxide is also an amphoteric oxide.
(c) Bronze contains copper and tin.

Question 11.
(a) Write the chemical name of the coating that forms on silver and copper articles when these are left exposed to moist air.
(b) Explain what is galvanisation. What purpose is served by it?
(c) Define an alloy. How are alloys prepared? How do the properties of iron change when:
(i) small quantity of carbon,
(ii) nickel and chromium are mixed with it.    (CBSE 2012)
Answer:
(a) On silver, silver sulphide layer is formed and on copper, copper carbonate layer is formed.
(b) The coating of zinc metal over the surface of iron metal is called galvanization. It is done to prevent the rusting of iron.
(c) Alloy is a homogeneous mixture of two or more metals or metal and non-metals. They are prepared by melting the two components of alloy metals together.
(i) On adding small quantity of carbon in iron, steel is obtained which does not rust.
(ii) iron, when mixed with nickel and chromium, forms an alloy named stainless steel which also does not rust.

Question 12.
(a) Differentiate between roasting and calcination. Explain the two with the help of suitable chemical equations. How is zinc extracted from its ore?
(b) Name two metals that can be used to reduce metal oxides to metals.   (CBSE 2012)
Answer:
(a) Roasting: It is a process in which sulphide ore is heated in the presence of oxygen to convert into oxide.
2Zns + 3O₂ → 2ZnO + 2SO₂
Calcination: It is a process in which carbonate ore is heated in the absence of air to form oxide.
ZnCO₃(s) → ZnO(s) + CO₂(g)
After calcination, Zn can be extracted by reduction with carbon.
Reduction: ZnO + C → Zn + CO
(b) Aluminium, Magnesium.

Question 13.
(a) In the formation of compound between two atoms A and B, A loses two electrons and B gains one electron.
(i) What is the nature of bond between A and B?
(ii) Suggest the formula of the compound formed between A and B.
(b) On similar lines explain the formation of MgCl₂ molecule.
(c) Common salt conducts electricity only in the molton state. why?
(d) Why is melting point of NaCl high?     (CBSE 2012)
Answer:

(c) Na⁺ and Cl^– are free to move in molten state but not in solid state.
(d) It is due to strong force of attraction between Na⁺ and Cl^–.

Question 14.
(a) Carbon cannot be used as reducing agent to obtain Mg from MgO. Why?
(b) How is sodium obtained from molten sodium chloride? Give equation of the reactions.
(c) How is copper obtained from its sulphide ore? Give equations of the reactions.   (CBSE 2012)
Answer:
(a) It is because ‘Mg’ is more reactive or stronger reducing agent than carbon.
(b) Sodium is obtained from molten NaCl by electrolysis.
\(\underset{\text { (Molten })}{2 \mathrm{NaCl}} \stackrel{\text { electrolysis }}{ } \rightarrow 2 \mathrm{Na}(\mathrm{s})+\mathrm{Cl}_{2}(\mathrm{g})\)
At anode: 2Cl^– → Cl₂(g) + 2e^–
At cathode: 2Na⁺ 2e^– → 2Na(s)
(c) Copper ore is concentrated by froth-floatation process.
Roasting:

Copper oxide reacts with Cu₂S on heating to form Blister copper and SO₂.

Question 15.
How is the method of extraction of metals high up in the reactivity series different from that for metals in the middle? Why the same process cannot be applied for them? Explain giving equations, the extraction of sodium. (CBSE 2012)
Answer:
Metals high up in the series are obtained by electrolytic reduction because these metals are strong reducing agents and therefore, cannot be obtained by chemical reduction.

Metals in middle of series are less reactive and can be obtained by chemical reduction with the metals that lie above in the series. The same process cannot be used for both of them as highly reactive metals cannot be obtained by chemical reduction. Extraction of sodium is done by electrolysis of molten sodium chloride.

Question 16.
Write the names and symbols of two most reactive metals. Explain by drawing electronic structure how any one of the two metals react with a halogen. State any four physical properties of the compound formed.    (CBSE 2012)
Answer:
K(Potassium) and Na(Sodium) are the two most reactive metals.

where ‘F’ is a halogen.
Four physical properties of the compounds formed by these elements and halogens are:
(i) They have high melting point.
(ii) They are soluble in water.
(iii) They conduct electricity in molten state, not in solid state.
(iv) They are solid and somewhat hard.

Question 17.
Give reasons for the following:
(i) Silver and copper lose their shine when they are exposed to air. Name the substance formed on their surface in each case.
(ii) Tarnished copper vessels are cleaned with tamarind juice.
(iii) Aluminium is more reactive than iron, yet there is less corrosion of aluminium as compared to iron when both are exposed to air.    (CBSE 2012)
Answer:
(i) These metals get corroded. Silver forms black Ag₂S (silver sulphide) and copper form greenish layer of CuCO₃ (copper carbonate).
(ii) Tamarind contains acid which reacts with basic copper carbonate and product gets dissolved and removed from copper vessel.
(iii) Aluminium forms oxide layer on its surface which does not further react with air.

Question 18.
(a) Write the electron dot structures of sodium, oxygen and magnesium.
(b) Show the formation of Na₂O and MgO by transfer of electrons. Name the ions present in these compound.
(c) List three properties of ionic compounds.    (CBSE 2012)
Answer:


Na₂O contains Na⁺ and O^2- ions.
MgO contains Mg²⁺ and O^2- ions.

(c) (i) They are solids having high melting point.
(ii) They are soluble in water.
(in) They conduct electricity in molten state as well as in aqueous solution.

Question 19.
What are alloys? How are they made? Name the constituents and uses of brass, bronze and solder.    (CBSE 2012)
Answer:
Alloys are homogenous mixtures of two of more metals. One of them can be a non-metal. They are made by melting a metal which is in large amount and then add the other metal in molten form. Brass contains copper and zinc. It is used for making decorative articles. Bronze contains copper and tin. It is used for making statues and medals. Solder contains lead and tin. It is used for soldering purposes.

Question 20.
A metal (E) is stored under kerosene. When a small piece of it is left open in the air, it catches fire. When the product formed is dissolved in water, it turns red litmus to blue.
(i) Name the metal (E).
(ii) Write the chemical equation for the reaction when it is exposed to air and when the product is dissolved in water.
(iii) Explain the process by which the metal is obtained from its molten chloride.     (CBSE 2012)
Answer:
(i) Metal E is sodium
(ii) Reaction of sodium metal with air is:
4Na + O₂ → 2Na₂O
When the product formed is dissolved in water:
Na₂O + H₂O → 2NaOH
(iii) The molten chloride of sodium metal is NaCl, the metal can be obtained by the electrolytic reduction. The current is allowed to pass through the molten sodium chloride using the two carbon electrodes. The sodium metal is obtained at the cathode and the chlorine gas is collected at the anode.
2NaCl → 2Na + Cl₂

Question 21.
Write two differences between calcination and roasting.   (CBSE 2012)

Question 22.
You are provided with magnesium ribbon and sulphur powder. Explain with the help of an activity that metal oxides are basic and non-metal oxides are acidic in nature.    (CBSE 2014)
Answer:
Activity:

• Take magnesium ribbon with a pair of tongs and bum it in flame in the presence of air.
• Collect the product formed and dissolve it in warm water.
• Add red litmus paper into it.
• Observe the change in colour and decide the nature of the oxide formed.
• Bum sulphur in a deflagrating spoon in the presence of air, collect the gas in an inverted test tube and dissolve the oxide formed in water.
• Dip blue litmus paper into the solution and observe the change in the colour and decide the nature of the oxide formed.

Observation:
The oxide formed by magnesium metal turns red litmus blue whereas oxide of sulphur, a non-metal turns blue litmus red.
Chemical Reactions:

Conclusion: Most of the metallic oxides are basic in nature whereas most of the non- metallic oxides are acidic.

Question 23.
(a) An ore on treatment with dilute hydrochloric acid produces brisk effervesces.
What type of ore is this? What steps will be required to obtain metal from the enriched ore.
(b) Copper coin is kept immersed in silver nitrate solution for some time. What change will take place in coin and colour of the solution? Write balanced chemical equation of the reaction involved.    (CBSE 2014)
Answer:
(a) Carbonate ore:
(i) Calcination: Carbonate ore is heated in limited supply of air and oxide is obtained, e.g.
ZnCO₃(s) → ZnO(s) + CO₂(g)
(ii) Reduction with carbon: Oxide ore is then heated with carbon to obtain metal.
ZnO(s) + C(s) → Zn(s) + CO(g)
(b) Copper, being more reactive than silver, will displace silver from silver nitrate solution and there will be deposition of silver on copper coin. The colour of solution will turn to blue.
Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq) + 2Ag(s)

Question 24.
(a) Write electron dot diagram for chlorine (at no. 17) and calcium (at no. 20). Show the formation of calcium chloride by transfer of electrons.
(b) Identify the nature of above compound and explain three physical properties of such compound.   (CBSE 2015)
Answer:

(b) It is ionic compound.
Physical properties

1. It is hard and solid.
2. It has high melting and boiling point.
3. It is soluble in water.

In this page you can find Memories of Childhood Extra Questions and Answers Class 12 English Vistas, Extra Questions for Class 12 English will make your practice complete.

Memories of Childhood Extra Questions and Answers Class 12 English Vistas

Memories of Childhood Extra Questions and Answers Short Answer Type

Question 1.
How was Zitkala-Sa different from the other Native American students?
Answer:
Zitkala-Sa was a Native American girl. She had great love for her tradition and culture. She was proud of her beliefs. She held these beliefs close to her heart and felt hurt when the rest of the girls followed the foreign culture without any hesitation.

Question 2.
Mention any two reasons because of which it would take thirty minutes to an hour for Bama to reach home?
(Memories of Childhood—We too are human beings)
OR
What would take ‘Bama’ half an hour to cover ten minutes distance?
Answer:
There were many reasons why Bama took long to reach home. She would watch all the fun and games going on the road, she would also look at the shops and bazaars; she loved looking at the performing monkey and the snake charmers. The various food stalls, the street plays, the political meetings, the Maariyaata temple, the pongal offerings being cooked in front of the temple she could just go on and on looking at the beautiful sights.

Question 3.
Why was the girl tied to a chair in Memories of Childhood?
Answer:
The girl, Zitkala-Sa was refusing to accept the school’s decision to shingle the hair of all girls. According to her traditions and customs, a girl’s long hair was shingled only when captured by enemy, in mourning or for cowards. She felt insulted and hid herself. She was finally caught and forcefully tied to a chair and her long hair was chopped off.

Question 4.
Why did Zitkala-Sa not want her hair to be cut short?
Answer:
Zitkala-Sa belonged to a Native American warrior tribe. Their tradition was to keep long and heavy hair. Only those warriors, captured by the enemy, had their hair shingled. Short hair was worn by mourners, and shingled hair by cowards. Therefore, for her, this was absolutely atrocious.

Question 5.
When did Bama first come to know of the social discrimination faced by the people of her community?
Answer:
Bama came to know of the social discrimination when she was in class 3. On her way back from school, she saw an elder from her community carrying a small packet of eatables by a string without touching it. She found it very funny that a huge elderly man was carrying a small packet so strangely. Later on, she discovers from her brother that the real reason was that the landlords were of a higher class and they thought that their food would get polluted, if touched by people from her caste.

Question 6.
How did Zitkala-Sa try to prevent the shingling of her hair?
OR
Describe how Zitkala-Sa tried in vain to save her hair from being cut. Why did she want to save her hair?
Answer:
Zitkala-Sa went upstairs and crawled under a bed to hide herself. But to her plight, she was caught and brought downstairs and tied to a chair. Though she made many voluble protests, they were not fruitful. She cried, shook her head all the while but could not avoid her hair from being shingled.

Zitkala-Sa belonged to a Native American warrior tribe. Their tradition was to keep long and heavy hair. Only those warriors captured by the enemy had their hair shingled. Short hair was worn by mourners, and shingled hair by cowards. Therefore, for her, this was absolutely atrocious.

Question 7.
What are the similarities in the lives of Bama and Zitkala-Sa though they belong to different cultures?
OR
What kind of discrimination did Bama and Zitkala-Sa experience? How did they respond to their respective situations?
Answer:
Both Bama and Zitkala-Sa are victims of racial discrimination. Zitkala-Sa was a Native American and their community was treated poorly. The white skinned settlers of Europe considered local tribes as inferior. Similarly, Bama was a Dalit and was treated badly by the higher caste people.

Both of them have painful experiences as they were subjected to humiliation merely as they belonged to backward tribes or communities. Both of them protest in their own ways and try their best to overcome all these humiliations. Zitkala-Sa fights against the shingling of hair by hiding, voicing out her protests aloud. Bama tries to study hard and be successful.

Question 8.
How was Zitkala-Sa’s hair cut?
Answer:
Zitkala-Sa’s hair was cut even after her resistance and strong opposition. It was all in vain since her stiff resistance was met with equally stiff efforts. She was tied to a chair and amidst her loud disapproval, her hair was cut.

Question 9.
Why did the landlord’s man ask Bama’s brother, on which street he lived? What was the significance?
Answer:
The street on which a person lived signified the caste of a person. Each street was dominated by a particular caste.

Question 10.
What did Zitkala-Sa feel when her long hair was cut?
Answer:
Zitkala-Sa was terribly shocked. She was in tears. She cried for her mother. However, no one came to comfort or reason out with her.

Question 11.
Why was Zitkala-Sa terrified when Judewin told her that her hair would be cut short?
Answer:
Judewin had overheard a talk about shingling of hair of all girls. Zitkala-Sa belonged to a native American warrior tribe. Their tradition was to keep long and heavy hair. Only those warriors captured by the enemy had their hair shingled. Short hair was worn by mourners, and shingled hair by cowards. Therefore, for her, this was absolutely atrocious and terrifying. Therefore, she decided to rebel by hiding herself.

Question 12.
What advice did Annan offer Bama?
Answer:
Annan asked Bama to study hard and to top all exams. He also told her that if she was successful in life, people would come to her of their own accord.

Question 13.
At the dining table, why did Zitkala-Sa begin to cry when others started eating?
Answer:
Zitakala-Sa was not used to eating by formula. She was confused and sat down when others stood up and vice versa. She felt out of place and embarrassed in the school. The matron was angry with her and kept staring at her. This made Zitkala-Sa more uncomfortable and she started crying when the others started eating.

Question 14.
How did Zitkala-Sa’s first day in the land of apples begin?
Answer:
The first day in school was a bitter and cold day. The noise made by the breakfast bell, the clatter of the shoes and the constant murmuring voices in a foreign tongue annoyed Zitkala-Sa. She saw girls marching into dining room wearing tight fitting clothes. Zitkala-Sa found this immodest.

Question 15.
According to Zitkala-Sa, what does ‘eating by formula’ mean?
Answer:
There was a fixed procedure for breakfast. With the first bell, everyone had to pull the chairs, at the second bell, everyone had to sit down. Finally, at the third bell, everyone had to start eating with forks and knives. Zitkala-Sa called it eating by formula. She felt out of place and started crying.

Question 16.
What were the indignities that Zitkala-Sa had to suffer for being from a marginalised community?
Answer:
Zitkala-Sa was tied with the chair and her braids were gnawed off. She became helpless. She felt herself like a wooden puppet tossed in the air. She felt herself like one of those sheep (cattle) driven by a herder.

Memories of Childhood Extra Questions and Answers Long Answer Type

Question 1.
Describe how the narrator in ‘The Cutting of My Long Hair’ resists and fights against ‘ the attempt of shingling her long and heavy hair. How is she ultimately made to lose her distinct cultural identity?
Answer:
The narrator’s friend Judewin gave her a terrible warning. She knew a few words of English. She had overheard the ‘pale-faced woman’. She had talked about cutting the long and heavy hair of Native American girls. It was a shocking news. Their mothers had taught them that shingled hair was worn only by cowards. Judewin advised her to submit. The narrator had made a decision. She was not to submit. She was to struggle and fight against that oppression.

The narrator disappeared unnoticed. She crawled under the bed and cuddled herself in the dark corner. She shuddered with fear, whenever she heard footsteps nearby. Voices became louder.

They stormed into the room. She was dragged out. She resisted by kicking and scratching wildly. She was carried downstairs and tied fast to a chair. Then they gnawed off her long and beautiful hair. No one came forward to help her. Nor was anybody present there to console her. Thus, the narrator lost her distinct cultural recognition and identity. Now, she was only one of the many little animals driven by a herder.

Question 2.
The narrator in ‘We Too Are Human Beings’ is amused at the way the elder of her street carried the food packet by its string without touching it. But the same girl is provoked and becomes angry when Annan makes her aware of the social inequality and untouchability in the social system. Describe how the narrator attains honour and dignity in spite of her humble birth.
Answer:
The narrator in ‘We Too Are Human Beings’ passes through different phases of mental and physical development. The role of her elder brother (Annan) in shaping her personality can’t be minimised. He inspired her to fight against inequality and untouchability. The narrator saw a threshing floor set up at one corner of her street. An old man of her street attracted her attention. The elder came along from the direction of the bazaar.

He was a big man carrying a small packet of food by its string without touching it. She thought it quite funny. She narrated the incident to her elder brother, but he was not amused. The man was not being funny. He belonged to a ‘low caste’. He couldn’t touch the food packet. She
felt terribly sad. She felt provoked and angry that she wanted to touch those vadais herself straightaway. Annan described that the people of their caste were not respected and given importance.

Education, learning and prosperity bring honour and dignity.The narrator was inspired by his words. She studied hard and stood first in the class. Then many friends came to her on their own accord.

Question 3.
Both Bama and Zitkala-Sa are victims of discrimination that is practised in the society. What kind of experience did both of them go through?
Answer:
The lesson, ‘Memories of Childhood’ deals with the autobiographical accounts of women of marginalised communities. Both narrate the prejudices and humiliation faced by them from mainstream culture. The former is a victim of racial discrimination, whereas the latter is a victim of caste discrimination.

Solved the very best collection of Acids, Bases and Salts Class 10 Science Important Questions and Answers Chapter 2 Pdf from the latest NCERT edition books, It will help you in scoring more marks in CBSE Exams.

Acids, Bases and Salts Class 10 Important Questions with Answers Science Chapter 2

Acids, Bases and Salts Class 10 Important Questions Short Answer Type

Question 1.
(a) Give Arrhenius definition of an acid and a base.   (CBSE 2006)
(b) Choose a strong acid and strong base from the following:
CH₃COOH, NH₄OH, KOH, HCl
Answer:
(a) Arrhenius definition for
Acid: Acids are those substances which release H⁺ ions when dissolved in water.
Base: Bases are those substances which release OH^– ions when dissolved in water,
(b) The strong acid is HCl and strong base is KOH.

Question 2.
(a) Write the formula and chemical name of bleaching powder.
(b) Write chemical equation to represent the action of atmospheric CO₂ gas on bleaching powder when left exposed in open.
(c) State for what purpose is bleaching powder used in water treatment plants.   (CBSE 2006)
Answer:
(a) CaOCl₂ (Calcium oxychloride)

(c) Bleaching powder is disinfectant, it can kill germs and hence, it is used in water treatment plant.

Question 3.
How will you test for the gas which is liberated when hydrochloric acid reacts with an active metal? (CBSE 2008/2012)
Answer:
An active metal reacts with hydrochloric acid to give hydrogen gas. When a burning splinter is brought close to the gas evolved, pop sound is produced and the gas continues to burn.

Question 4.
What is ‘Baking Powder’? How does it make the cake soft and spongy?   (CBSE 2008)
Answer:
Baking powder is a mixture of baking soda and tartaric acid.
When baking powder is heated it releases CO₂ gas due to which the cake rises and becomes soft and spongy.

Question 5.
What happens chemically when quick lime is added to water?   (CBSE 2008)
Answer:
Quick lime reacts with water to form calcium hydroxide (slaked lime) and large amount of heat is released (exothermic reaction) with a hissing sound.
CaO + H₂O → Ca(OH)₂ + heat

Question 6.
Name the gas evolved when dilute HCl reacts with sodium hydrogen carbonate. How is it recognised? (CBSE 2008)
Answer:
The gas evolved is CO₂.
It can be recognised by passing it through lime water (freshly prepared), the lime water turns milky.
Ca(OH)₂ + CO₂ → CaCO₃

Question 7.
How does the flow of acid rainwater into a river make the survival of aquatic life in the river difficult?   (AI 2008)
Answer:
Acid rain water when flows into the river the pH of river water decreases, which makes the aquatic life difficult to survive. The pH range suitable for aquatic survival is 7.0 to 7.8 and due to acid rainwater pH of river water decreases.

Question 8.
How is the pH of a solution of acid influenced when it is diluted?   (Foreign 2008)
Answer:
Acid when dissolved in water the H⁺ concentration in moles per litre decreases and therefore pH will increase, as the solution becomes less acidic on dilution.

Question 9.
How does the pH of the solution change when a solution of the base is diluted?    (Foreign 2008)
Answer:
Based on dilution with water become less basic in nature and their pH decreases.
(e.g. pH of the strong base would be 14, on diluting its pH becomes below 14)

Question 10.
Arrange the following in increasing order of their pH values:
NaOH soln, blood, lemon juice. (Foreign 2008)
Answer:
Lemon juice < Blood < NaOH solution.

Question 11.
Two solutions A and B have pH values of 5 and 8 respectively. Which solution will be basic in nature?  (CBSE 2008C)
Answer:
B will be basic nature, with pH = 8.

Question 12.
A compound ‘X’ of sodium is commonly used in kitchen for making crispy pakoras. It is also used for curing acidity in the stomach. Identify ‘X’. What is its chemical formula? State the reaction which takes place when it is heated during cooking.   (CBSE 2008C)
Answer:
‘X’ is sodium hydrogen carbonate (baking soda)
Chemical formula → NaHCO₃
During cooking → It decomposes to sodium carbonate, carbon dioxide and water

Question 13.
Fresh milk has a pH of 6. When it changes into curd (yoghurt) will it pH value increase or decrease? Why?  (CBSE 2009)
Answer:
When fresh milk turns into curd, its pH value will decrease. This is because lactic acid is produced when milk changes into curd.

Question 14.
A compound which is prepared from gypsum has the property of hardening when mixed with a proper quantity of water. Identify the compound. Write the chemical equation for its preparation. For what purpose is it used in hospitals?     (CBSE 2009)
Answer:
The compound is calcium sulphate hemihydrate, Plaster of Paris CaSO₄. \(\frac{1}{2}\)H₂O.

It is used in hospitals for a plaster cast.

Question 15.
Why does tooth decay start when the pH of mouth is lower than 5.5?    (CBSE 2009)
Answer:
When the pH in mouth is lower than 5.5, it means acids are formed due to food decay by bacteria in our mouth. The acid released reacts with enamel, which is made up of calcium phosphate and tooth decay starts.

Question 16.
What would be the colour of litmus in a solution of sodium carbonate?   (CBSE 2009)
Answer:
Red litmus will change to blue colour in solution of sodium carbonate.

Question 17.
What effect does an increase in concentration of H⁺(aq) in a solution have on the pH of solution?   (AI 2009)
Answer:
If the concentration of H⁺ ions in a solution increases, then the pH of solution decreases.

Question 18.
(i) Name the products obtained when sodium hydrogen carbonate is heated.
(ii) Write the chemical equation for the reaction involved in the above.   (AI 2009)
Answer:
(i) When sodium hydrogen carbonate is heated. Sodium carbonate, carbon dioxide and water is formed.

Question 19.
Which of these has a higher concentration of H⁺ ions – 1 M HCl or 1M CH₃COOH?   (AI 2009)
Answer:
1M HCl has higher concentration of H⁺ ions.

Question 20.
Crystals of copper sulphate are heated in a test tube for some time.
(a) What is the colour of copper sulphate crystals
(i) before heating and
(ii) after heating?    (AI 2009)
(b) What is the source of liquid droplets seen on inner side of tube?
Answer:
(a) (i) Colour of copper sulphate crystals before heating is blue.
(ii) After heating blue colour disappears and turns white.
(b) It is the water of crystallisation.

Question 21.
Why does 1M HCl solution have a higher concentration of H⁺ ions than 1M CH₃COOH solution?   (AI 2009)
Answer:
HCl being a strong acid ionise completely to give more H⁺ ion than CH₃COOH (a weak acid which ionise partially) of equal concentration.

Question 22.
Write the name and chemical formula of the calcium compound used for disinfecting drinking water. How is this compound manufactured?   (AI 2009)
Answer:
Bleaching powder – CaOCl₂
Preparation: On passing chlorine gas through slaked lime, CaOCl₂ is formed.

Question 23.
Which gas is generally liberated when a dilute solution of hydrochloric acid reacts with an active metal?   (Foreign 2009)
Answer:
Hydrogen gas is liberated when a dilute solution of hydrochloric acid reacts with an active metal.
e.g. Zn(s) + 2HCl(dil) → ZnCl₂(aq) + H₂(g)

Question 24.
What is the colour of litmus in a solution of ammonium hydroxide?   (Foreign 2009)
Answer:
Red litmus turns blue in solution of ammonium hydroxide.

Question 25.
What is an alkali?   (Foreign 2009)
Answer:
Bases soluble in water are called alkali.

Question 26.
(a) Write the name given to bases that are highly soluble in water. Give an example,
(b) How is tooth decay related to pH? How can it be prevented?
(c) Why does bee sting cause pain and irritation? Rubbing of baking soda on the sting area gives relief. How?   (CBSE 2012)
Answer:
(a) Alkali, e.g., NaOH (Sodium hydroxide).
(b) Lower the pH, more will be tooth decay. Acid reacts with Ca₃(PO₄)₂ and cause tooth decay. It can be prevented by brushing teeth after every meal.
(c) It is due to formic acid. Sodium hydrogen carbonate (Baking soda) neutralises formic acid giving relief.

Question 27.
A white powder is added while baking breads and cakes to make them soft and fluffy. Write the name of the powder. Name its main ingredients. Explain the function of each ingredient. Write the chemical reaction taking place when the powder is heated during baking.   (CBSE 2012)
Answer:
Baking powder. It consists of sodium hydrogen carbonate and tartaric acid. Sodium hydrogen carbonate on heating gives C02 which makes cake soft and fluffy. Tartaric acid neutralizes the bitterness due to sodium carbonate produced.

Question 28.
“Sodium hydrogen carbonate is a basic salt”. Justify the statement. How is it converted into washing soda? Explain. (CBSE 2012)
Answer:
Sodium hydrogen carbonate is a salt of sodium hydroxide (strong base) and carbonic acid (weak acid).
Thus, it is a basic salt. It is converted into washing soda by heating followed by crystallization.

Question 29.
A student detected the pH of four unknown solution A, B, C and D as follows 11, 5, 7 and 2. Predict the nature of the solution.   (CBSE 2013)
Answer:
A is basic ‘B’ is acidic ‘C’ is natural and ‘D’ is strongly acidic.

Question 30.
(i) Give the constituents of baking powder.
(ii) Why cake or bread swells on adding baking powder? Write chemical equation.    (CBSE 2013)
Answer:
(i) Baking powder contain sodium hydrogen carbonate and tartaric acid.
(ii) It is due to carbon dioxide
\(2 \mathrm{NaHCO}_{3}(\mathrm{s}) \stackrel{\text { heat }}{\longrightarrow} \mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(l)\)

Question 31.
Equal length of magnesium ribbon are taken in two test tubes A’ and ‘B’, H₂SO₄ is added to test tube ‘A’ and H₂CO₃ in the test tube ‘B’ in equal amounts:       (CBSE 2013)
(a) Identify the test tube showing vigorous reaction.
(fa) Give reason to support your answer.
(c) Name the gas liberated in both the tubes. How will you prove its liberation?
(d) Write chemical equations for both reactions.
(e) Out of the two acids taken above
(i) which one will have lower pH value.
(ii) lower H⁺ concentration respectively.
Answer:
(a) A will show vigorous reaction.
(b) It is because H₂SO₄ is strong acid.
(c) Hydrogen gas will be formed. Bring a burning splinter near the gas. It will burn with ‘pop’ sound. It shows gas liberated is hydrogen.
(d) Mg + H₂SO₄ → MgSO₄ + H₂
Mg + H₂CO₃ → MgCO₃ + H₂
(e) ‘A’ (H₂SO₄) will have lower pH.
‘B’ (H₂CO₃) will have lower concentration of H⁺

Question 32.
Name the natural source of each of the following acid.
(i) Citric acid.
(ii) Oxalic acid.
(iii) Lactic acid.
(iv) Tartaric acid.     (CBSE 2014)
Answer:
(i) Lemon and orange
(ii) Tomatoes and Guava.
(iii) Sour milk (curd)
(iv) Tamarind.

Question 33.
Explain the action of dilute hydrochloric acid on the following with chemical equation:
(i) Magnesium ribbon
(ii) Sodium hydroxide
(iii) Crushed egg shells.    (CBSE 2015)
Answer:
(i) Hydrogen gas will be formed
Mg(s) + 2HCl (dil) → MgCl₂(aq) + H₂(s)
(ii) Sodium chloride and water will be formed
NaOH + HCl → NaCl + H₂O
(iii) Crushed egg shell are made up of CaCO3 which reacts with dil HCl to give brisk
effervescence due to CO₂.
CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

Question 34.
Name the acid present in the following:
(i) Tomato
(ii) Vinegar
(iii) Tamarind   (CBSE 2015)
Answer:
(i) Oxalic acid
(ii) Acetic acid
(iii) Tartaric acid

Question 35.
15 ml of water and 10 ml of sulphuric acid are to be mixed in a beaker
(i) State the method that should be followed with reason.
(ii) What is this process called?    (CBSE 2015)
Answer:
(i) The acid is to be added slowly in water to prevent the mixture to be splashed.
The reaction is highly exothermic, therefore, constant cooling should be done
(ii) The process is called dilution.

Question 36.
(a) Define olfactory indicators. Name two substances which can be used as olfactory indicator.
(b) Choose strong acids from the following:
CH₃COOH, H₂SO₄, H₂CO₃, HNO₃       (CBSE 2015)
Answer:
(a) Those substances whose smell (odour) changes in acidic or basic solution are called olfactory indicators, e.g., onion and vanilla.
(b) H₂SO₄ and HNO₃ are strong acids.

Question 37.
A white coloured powder is used by doctors for supporting fractured bones.
(a) Write chemical name and formula of the powder
(b) When this white powder is mixed with water a hard solid mass is obtained.
Write balanced chemical equation for the change.      (CBSE 2015)
Answer:

Acids, Bases and Salts Class 10 Important Questions Long Answer Type

Question 1.
What is meant by water of crystallisation in a substance? How would you show that blue copper sulphate crystals contain water of crystallisation?     (CBSE 2008)
Answer:
Water of crystallization is fixed number of water molecules present in the crystalline state of salt.
e.g., CUSO₄.5H₂O Copper sulphate [Blue vitriol]
FeSO₄.7H₂O Ferrous sulphate [Green vitriol]

To show the water of crystallisation in copper sulphate:
Take a dry boiling test tube, add few crystals of blue copper sulphate and heat it on the flame. Water vapour collects on the inner sides of the test tube. The colour of copper sulphate changes to white.

On cooling add few drops of water to anhydrous copper sulphate (white powder obtained) it turns blue.

Question 2.
Write the chemical formula for washing soda. How may it be obtained from baking soda? Name an industrial use of washing soda other than washing clothes.     (AI 2008)
Answer:
Washing soda → Na₂CO₃ + 10H₂O. (sodium carbonate decahydrate)
Baking soda on heating produces sodium carbonate which is then recrystallised.
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
Na₂CO₃ + 10H₂O → Na₂CO₃.10H₂O
It is used in the manufacture of glass and paper.

Question 3.
Write the chemical formula of bleaching powder, how is bleaching powder prepared?
For what purpose is it used in paper factories?     (AI 2008)
Answer:
Bleaching powder – CaOCl₂
Preparation: On passing chlorine gas over slaked lime (Ca(OH)₂), bleaching powder is obtained.
Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O
Use: It is used in paper industry for bleaching paper.

Question 4.
Write the chemical formula of washing soda and baking soda. Which one of these two is an ingredient of antacids? How does it provide relief in stomach ache?       (Foreign 2008)
Answer:
Washing soda – Na₂CO₃.10H₂O (Sodium carbonate decahydrate)
Baking soda – NaHCO₃ (Sodium bicarb3onate)
Baking soda is used as an antacid it neutralises excess acid in the stomach and provides relief.

Question 5.
Solid calcium oxide was taken in a container and water was added slowly to it.
(i) State the two observations made in the experiment.
(ii) Write the name and chemical formula of the product formed.    (AI 2008C)

Answer:
(i) A large amount of heat is evolved → Exothermic reaction
The reaction takes place vigorously with hissing noise and bubbles.
(ii) Ca(OH)₂   (Calcium hydroxide), common name is slaked lime.

Question 6.
(a) Why does an aqueous solution of an acid conduct electricity?
(b) How does the concentration of hydronium ions (H₃O⁺) change when a solution of an acid is diluted?
(c) Which has higher pH value, a concentrated or dilute solution of hydrochloric acid?
(d) What do you observe on adding dilute hydrochloric acid to
(i) Sodium carbonate placed in test tube.
(ii) Zinc metal in a test tube?    (AI 2008C)
Answer:
(a) Aqueous solution of an acid releases ions so that it can conduct electricity.
(b) When solution of an acid is diluted, concentration of hydronium ions (H₃O⁺) decreases.
(c) Dilute solution of HCl will have higher pH than concentrated solution.
(d) (i) Na₂CO₃ + 2HCl(dil.) → 2NaCl + CO₂ + H₂O
Effervescence of CO₂ gas is seen.
(ii) Zn(s) + 2HCl(dil.) → ZnCl₂ + H₂(g)
Odourless and colourless gas hydrogen is evolved with bubbles on surface of zinc.

Question 7.
What is meant by ‘water of crystallisation’ of a substance? Describe an activity to show that blue copper sulphate crystals contain water of crystallisation.     (Foreign 2009)
Answer:
The water molecules associated with a crystalline substance is called ‘water of crystallisation’.
Activity → Take few crystals of blue copper sulphate in a dry boiling tube. Heat it
on flame, the blue crystals change to white dry powder and the inner surface of the test tube condenses with water.
This proves that crystals contain water molecules in it. If we add some water in the white powder it regains the lost water molecules and become blue again.

Question 8.
(a) Identify the acid and the base whose combination forms the common salt that you use in your food. Write its formula and chemical name of this salt. Name the source from where it is obtained.
(b) What is rock salt? Mention its colour and the reason due to which it has this colour.
(c) What happens when electricity is passed through brine? Write the chemical
equation for it.        (CBSE 2012)
Answer:
(a) HCl is acid and NaOH is base whose combination forms the common salt. Its formula is NaCl (Sodium chloride). It is obtained from seawater.
(b) Rock salt is the common name for the mineral “halite”. Its chemical formula is NaCl. It may be white or light blue or yellow depending upon impurities present
in it.
(c) Brine is the aqueous solution of NaCl which undergoes electrolysis on passing current and forms H₂ and Cl₂ gases with NaOH as aqueous solution.
\(2 \mathrm{NaCl}+2 \mathrm{H}_{2} \mathrm{O} \stackrel{\text { electrolysis }}{\longrightarrow} 2 \mathrm{NaOH}+\mathrm{H}_{2}+\mathrm{Cl}_{2}\)

Question 9.
(i) Explain why is hydrochloric acid a strong acid and acetic acid, a weak acid. How can it be verified?
(ii) Explain why aqueous solution of an acid conducts electricity.
(iii) You have four solutions A, B, C and D. The pH of solution A is 6, B is 9, C is 12 and D is 7.
(a) Identify the most acidic and most basic solutions.
(b) Arrange the above four solutions in the increasing order of H⁺ ion concentration.
(c) State the change in colour of pH paper on dipping in solution C and D.      (CBSE 2012)
Answer:
(i) HCl is completely ionised in aqueous solution whereas acetic acid is partially ionised in aqueous solution. HCl gives dark red colour with pH paper whereas CH₃COOH gives orange colour.
(ii) It is because acid ionises in aqueous solution and these ions conduct electricity.
(iii) (a) ‘A’ is most acidic and ‘C’ is most basic.
(b) C(10^-12) < B (10^-9) < D(10^-7) < A(10^-6)
(c) pH paper will become blue in ‘C’ and green in ‘D’.

Question 10.
(i) Dry pellets of a base ‘X’ when kept in open absorbs moisture and turns sticky.
The compound is also formed by chlor-alkali process. Write chemical name and formula of X. Describe chlor-alkali process with balanced chemical equation. Name the type of reaction occurs when X is treated with dilute hydrochloric acid. Write the chemical equation.
(ii) While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid? (CBSE 2012)
Answer:
(i) X is sodium hydroxide, NaOH.
When sodium chloride solution (brine solution) is electrolysed, sodium hyroxide solution is formed. H₂ and Cl₂ gases are liberated. This is chlor-alkali process.

The above reaction is neutralization reaction.
(ii) It is because process is highly exothermic. If water is added to acid, it generates huge amount of heat which may cause accident but if acid is added dropwise to water, then the heat is absorbed by the solution.

Question 11.
A student dropped few pieces of marble in dilute hydrochloric acid, contained in a test-tube. The evolved gas was then passed through lime water. What change would be observed in lime water? What will happen if excess of gas is passed through lime water? With the help of balanced chemical equations for all the changes explain the observations.   (CBSE 2012)
Answer:
CaCO₃ + 2HCl (dil.) → CaCl₂ + H₂O + CO₂
Lime water will turn milky due to liberation of CO₂.
Ca(OH)₂(aq) + CO₂(g) → CaCO₂(s) + H₂O(l)
If excess of CO₂ gas is passed through lime water, milkiness will disappear due to the formation of Ca(HCO₃)₂(aq) which is soluble in water.
CaCO₃(s) + H₂O(l) + CO₂(g) → Ca(HCO₃)₂(aq)

Question 12.
(a) Identify the compound of calcium which is yellowish-white powder and is used for disinfecting drinking water. Write its chemical name and formula. How is it manufactured? Write the chemical equation for the reaction involved. Also list two other uses of the compound.
(b) Write the balanced chemical equation of Chlor-alkali process.    (CBSE 2012)
Answer:
(a) The compound is bleaching powder (CaOCl₂). Its chemical name is calcium oxychloride. It is manufactured by reaction of solid slaked lime with dry chlorine gas.
Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O
(i) It is used for bleaching purposes in laundary, textile and paper industries.
(ii) It is used for preparation of chloroform.

Question 13.
(a) Crystals of a substance changed their colour on heating in a closed test tube but regained it after sometime when they were allowed to cool down. Name the substance and write its formula and explain the phenomenon involved.
(b) Name the compound whose one formula unit is associated with 10 water molecules. How is it prepared? Give equations of related reactions. Give two uses of the compound.      (CBSE 2012)
Answer:

It regains its colour by absorbing water from atmosphere and becomes blue in colour.
CuSO₄ + 5H₂O → CuSO₄.5H₂O
(b) Na₂CO₃.10H₂O. It is called sodium carbonate decahydrate or washing soda. It is prepared by passing CO₂ gas through saturated solution of ammonical brine.

Uses:
(i) It is used in the production of washing powder.
(ii) It is used for the manufacture of glass.

Question 14.
(a) A metal compound ‘X’ reacts with dil. H₂SO₄ to produce effervescence. The gas evolved extinguishes a burning candle. If one of the compound formed is calcium sulphate, then what is ‘X’ and the gas evolved? Also, write a balanced chemical equation for the reaction which occurred.
(b) (i) Name one antacid. How does it help to relieve indigestion in stomach?
(ii) A farmer treats the soil with quicklime or calcium carbonate. What is the nature of soil? Why does the farmer treat the soil with quicklime? (CBSE 2012)
Answer:
(a) ‘X’ is CaCO₃ (calcium carbonate). The gas evolved is CO₂.
CaCO₃ + H₂SO₄ (dil.) → CaSO₄ + H₂O + CO₂
(b) (i) NaHCO₃ is antacid. It neutralizes excess of acid formed in the stomach.
(ii) The soil is acidic in nature. The farmer wants to make it neutral by adding quicklime which neutralise the acid in the soil.

Question 15.
(a) State the chemical properties on which the following uses of baking soda are based:
(i) as an antacid
(ii) as a soda acid fire extinguisher
(iii) to make bread and cake soft and spongy.
(b) How is washing soda is obtained from baking soda? Write balanced chemical equation.     (CBSE 2015)
Answer:
(a) (i) It is weakly basic in nature and naturalize hyperacidity
(ii) It liberates CO₂ with H₂SO₄, which extinguish fire.
(iii) It liberates CO₂ on heating which makes bread and cake soft and spongy.
(b) \(2 \mathrm{NaHCO}_{3} \stackrel{\text { heat }}{\longrightarrow} \mathrm{Na}_{2} \mathrm{CO}_{3}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O}\)
Baking soda on heating gives sodium carbonate which on crystallisation forms washing soda
Na₂CO₃ + 10H₂O → Na₂CO₃.10H₂O.

Question 16.
State reason for the following statements:
(i) Tap water conducts electricity whereas distilled water does not.
(ii) Dry hydrogen chloride gas does not turn blue litmus red whereas dilute hydrochloric acid does.
(iii) During summer season, a milk man usually adds a very small amount of baking soda to fresh milk.
(iv) For a dilution of acid, acid is added into water and not water into acid.
(v) Ammonia is a base but does not contain hydroxyl group.      (CBSE 2015)
Answer:
(i) Tap water contains ions which conduct electricity, distilled water does not contain ions.
(ii) Dry HCl does not form ions but dilute HCl gives H⁺ and Cl^– ions in solution.
(iii) Baking soda does not allow milk to change to lactic acid which makes milk sour.
(iv) Adding water to acid is highly exothermic. Therefore, water is added to acid very slowly with cooling.
(v) Ammonia dissolves in water and accept H⁺ from H₂Omolecules to release OH^– ions in solution. Therefore, it is basic in nature.

In this page you can find Journey to the end of the Earth Extra Questions and Answers Class 12 English Vistas, Extra Questions for Class 12 English will make your practice complete.

Journey to the end of the Earth Extra Questions and Answers Class 12 English Vistas

Journey to the end of the Earth Extra Questions and Answers Short Answer Type

Question 1.
What was Akademic Shokalskiy? Where was it headed and why?
Answer:
Akademic Shokalskiy was a Russian research vessel which was heading towards Antarctica, the coldest, driest, windiest continent in the world to become a part of Geoff Green’s ‘Students on Ice’ programme.

Question 2.
Describe the author’s emotions when she first set foot on Antarctica.
Answer:
Tishani Doshi’s initial reaction was relief as she had travelled for over hundred hours. This was followed by wonder at Antarctica’s white landscape and uninterrupted blue horizon, its immensity, isolation and at how there could have been a time when India and Antarctica could have been a part of the same landmass.

Question 3.
How is present day Antarctica different from Gondwana?
Answer:
Gondwana was a giant amalgamated southern supercontinent. The climate was much warmer, hosting a huge variety of flora and fauna. Gondwana thrived for about 500 million years. Subsequently, when dinosaurs were wiped out and the age of mammals happened, the landmass separated into countries, shaping the globe as we know it today.

Question 4.
Why does the author say that to visit Antarctica is to be a part of history?
Answer:
It is only when you visit Antarctica that you realise all that can happen in a million years, where we have come from and where we could possibly be heading. We understand the significance of Cordilleran folds, pre-Cambrian granite shields, ozone and carbon, evolution and extinction.

Question 5.
Why does Tishani Doshi describe her two weeks’ stay in Antarctica ‘a chilling prospect’?
Answer:
Accustomed to the warm climate of South India, being in a place where ninety per cent of the earth’s total ice is stored was a chilling prospect literally and metaphorically. It affected her metabolic and circulatory systems as well as her imagination.

Question 6.
Why does one lose all earthly perspective in Antarctica?
Answer:
The author compares it to walking into a giant ping-pong ball, devoid of any human markers. There are no trees, billboards, or buildings. The visual ranges from the microscopic to the mighty, from midges and mites to blue whales and icebergs.

Question 7.
Describe the brightness and silence that prevail in Antarctica during summer.
Answer:
Days go on and on in surreal twenty-four hour austral summer light, and an ubiquitous silence prevails, interrupted only by the occasional avalanche or calving ice-sheet.

Question 8.
Explain: ‘And for humans, the prognosis isn’t good’.
Answer:
The human civilisation has been around for a mere 12,000 years—barely a few seconds on the biological clock. Yet we have managed to etch our dominance over nature with concretisation, battling for limited resources, and unmitigated burning of fossil fuel. This has created a blanket of carbon dioxide around the world, which is increasing average global temperature.

Question 9.
Why is Antarctica a crucial element in all debates on climate change?
Answer:
Antarctica is the only place in the world that has never sustained a human population and is therefore, relatively ‘pristine’. More importantly, it holds in its ice cores half¬million-year-old carbon records trapped in its layers of ice.

Question 10.
What was the objective of the ‘Students on Ice’ programme?
Answer:
The ‘Students on Ice’ programme aims to take high school students to the ends of the world. It provides them with inspiring educational opportunities which fosters in them a new understanding and respect for our planet. It offers the future generation of policy makers a life-changing experience at an age when they are ready to absorb, learn and act.

Question 11.
What are the reasons for the success of the ‘Students on Ice’ programme?
Answer:
The author says that it is impossible to go so near the South Pole and remain unaffected. When you visibly see glaciers retreating and ice shelves collapsing, you begin to realise that the threat of global warming is very real.

Question 12.
What does the author describe as her best Antarctic experience?
Answer:
Just short of the Arctic Circle, this group of fifty-two people were made to walk on the ocean. The experience of walking on ice that seemed to stretch out forever, with the living, breathing ocean underneath, was nothing short of a revelation.

Question 13.
How did the Antarctica amaze the writer when she first saw it?
Answer:
The Antarctica is perhaps the coldest, and the driest continent. The writer felt wonder struck by its immensity, its isolation, its uninterrupted blue horizon. She was amazed as to how there was a time when India and Antarctica were part of the same landmass.

Question 14.
What was Gondwana? How did it look 650 million years ago?
Answer:
Gondwana was a super continent in the South. It was centred around Antarctica. 650 million years ago, there were no humans. The climate was much warmer, and a variety of flora and fauna thrived.

Journey to the end of the Earth Extra Questions and Answers Long Answer Type

Question 1.
What is the significance of the title, ‘Journey to the End of the Earth’?
Answer:
Tishani Doshi calls it a Journey to the end of this Earth’ because her journey was an educational one to Antarctica. She travelled aboard the ‘Academic Shokaskiy’, a Russian research vessel, along with a group of high school students, to learn more about the real impact of Global Warming and the future of planet Earth. They went to the coldest, driest, windiest continent in the world. Also, for the author, her journey started from Madras 13.09 degrees north of the Equator.

She crossed nine time zones, six check points, three bodies of water and as many ecospheres. After travelling for almost one hundred hours, in a car, aeroplane and a ship, she actually set foot on the Antarctic continent, which is in the extreme southern part of the earth, almost at its end. The warning signals that Antarctica gives are shocking and make the author realise that “the end of the earth” may become a metaphorical reality before long, unless humans take timely action.

Question 2.
Describe the impact of Antarctica on the author.
Answer:
Tishani Doshi describes her Antarctica experience as “nothing short of a revelation”. It was a mind boggling experience to travel to reach the coldest, windiest, and driest part of the world. She was filled with wonder at its vastness, seclusion and geological history. Its isolation and immensity made it difficult to understand that there may have been a time when India and Antarctica were a part of the same landmass. Spending two weeks where day and night merge in an austral summer light, where the only sounds are that of avalanche or calving ice-sheets was a transcending experience.

It gave her – an invaluable realisation: if we take care of small things, the big things will automatically fall into place, that everything is interconnected. Her experience of a walk on the ocean over a metre thick ice, with 180 metres of sea underneath, was an eye-opening one. She came away, marvelling at the beauty of balance in nature, and a realisation of the pressing need to preserve it.

Question 3.
What do we know about the geological history of Gondwana? How did the Antarctica become cold and barren?
Answer:
There was a super continent in the south about six-hundred-and-fifty million years ago. In the south, about 500 million years ago there were several changes. Dinosaurs were wiped out. Mammals began to develop. Gondwana was forced to break up into smaller landmasses. India drove away and jammed against Asia. It buckled its crust to form the Himalayas.

South America broke and drifted to join North America. It opened up the Drake Passage to create a cold current round the south pole. It left the Antarctica cold, isolated and barren. It is the coldest continent, having 90% of the earth’s total ice.

Question 4.
How is man blamed for despoiling the earth and climate changes? How can you see the effect of these changes in Antarctica?
Answer:
Human civilisation is new. However, during the short period man has lived, he has created confusion and disturbances. He gained dominance over nature by building cities, towns and villages. Since human population is ever increasing, the need of natural resources also increases. Man has been conflicting with other species to grab these exhaustible resources. He has burnt fossil fuels. This has led to a blanket of carbon dioxide around the earth. It has raised the average global temperature.

The rise in temperature has led to climatic changes. We cannot fully appreciate the effect of these changes. If you go to the Antarctica, it has not been spoiled by man. Its ecosystem is simple. Any change easily affects it, and is easily visible. That is why, the narrator involved students on ice expedition to save future generations.

In this page you can find Aunt Jennifer’s Tigers Extra Questions and Answers Class 12 English Flamingo, Extra Questions for Class 12 English will make your practice complete.

Aunt Jennifer’s Tigers Extra Questions and Answers Class 12 English Flamingo

Aunt Jennifer’s Tigers Extra Questions and Answers Short Answer Type

Question 1.
What ideology does Aunt Jennifer’s poem propound?
Answer:
The poem, ‘Aunt Jennifer’s Tigers’ is critical of the male world. It criticises the male society for terrifying and oppressing women like ‘Aunt Jennifer’.

Question 2.
How has Aunt Jennifer created her tigers? What traits of tigers do they reveal?
Answer:
Aunt Jennifer has embroidered the tigers on a panel with an ivory needle and wool. The tigers that she has created are wild and free bright golden yellow denizens of the green forest. They are fearless and bold, jumping around with confidence, totally opposed to her own character.

Question 3.
What do you mean by the certainty that the tigers possess?
Answer:
The tigers used to fear the men. But once they were made by Aunt Jennifer, they learnt courage. In their new birth, these tigers feel at ease and confident. Now, they do not have to run away from anyone. They move slowly and run ferociously.

Question 4.
How does the poet describe Aunt Jennifer’s tigers?
Answer:
The poet describes Aunt Jennifer’s tigers as ‘bright topaz denizens of the green forest’. They are fearless. They pace in ‘sleek’ chivalry.

Question 5.
What will happen to Aunt Jennifer’s tigers when she is dead?
Answer:
The tigers created by Aunt Jennifer are eternal. They will keep on prancing even after her death. These tigers are born out of her imagination in response to the oppression she goes through in the patriarchal society.

Question 6.
What is the weight that lies heavy on Aunt Jennifer’s hand? How is it associated with her husband?
Answer:
Aunt Jennifer had a troubled married life with a domineering and oppressing husband. She tries to find refuge in art to fight these demons, but even here, there is no respite. This makes her hand quiver so much that she finds it hard to knit.

Question 7.
How are the tigers different from her?
Answer:
The tigers of Aunt Jennifer are quite different from her. In fact, they are exactly opposite of her oppressed, submissive personality. The tigers are a symbol of strength, fierceness and beauty.

Question 8.
What picture of male chauvinism (tyranny) do we find in the poem, ‘Aunt Jennifer’s Tigers’?
Answer:
It shows constraints that a married woman experiences. Uncle’s wedding band on Aunt Jennifer’s hand symbolises oppressive band of patriarchal society. Aunt Jennifer is forced to live in accordance with the rules laid down by her husband. She does not have any freedom.

Question 9.
Aunt Jennifer’s efforts to get rid of her fear proved to be futile. Comment.
Answer:
Aunt Jennifer’s efforts to get rid of her fears proved futile. She embroiders tigers, a symbol of her desire of a free spirit. But her inner spirit has been jailed by the patriarchal society. The society did not show any concern for the Aunt’s suffering, or even her death. Her loss of freedom was her own loss.

Question 10.
In the poem ‘Aunt Jennifer’s Tigers’, what is the contrast between the reality of Aunt’s life and her imagination?
Answer:
Aunt Jennifer is timid, nervous and living a fearful existence in a male dominated atmosphere, whereas her tigers are bold, proud, fearless masters, prancing freely in their

Question 11.
How do ‘denizens’ and ‘chivalric’ add to our understanding of the tiger’s attitudes ?
Answer:
Tigers are the denizens of the world of green. The . tiger is considered very brave and courageous animal. They are not afraid of anyone.

Question 12.
Why do you think Aunt Jennifer’s hands are ‘fluttering through her wool’ in the second stanza ? Why is she finding the needle so hard to pull?
Answer:
Aunt Jennifer has become so old that it appears that her fingers are trembling through wool. She has become so weak that she even finds the needle hard to pull. The poet means to say that unending household chores have made aunt very weak.

Question 13.
What is suggested by the image ‘massive weight of Uncle’s wedding band’?
Answer:
The poet says that Uncle’s wedding band lies very heavily on Aunt Jennifer’s hand. She has to work endlessly from morning till night and also have to bear Uncle’s tyranny. Aunt Jennifer has to slavishly follow all the orders of uncle.

Question 14.
Of what or of whom is Aunt Jennifer terrified with in the third stanza?
Answer:
Aunt Jennifer is terrified of endless household chores and Uncle in the third stanza. She thinks that even after her death she will not be free from these household chores.

Question 15.
What are the ‘ordeals’ Aunt Jennifer is surrounded by, why is it significant that the poet uses the word ‘ringed’ ? What are the meanings of the word ‘ringed’ in the poem?
Answer:
Aunt Jennifer is surrounded by household chores. These chores are no less than ordeals for her be-cause willingly or unwillingly she has to do them. The word ‘ringed’ has been used to convey that Aunt Jennifer is so surrounded by her ordeals that she can never think to come out of them.

Question 16.
Why do you think Aunt Jennifer created animals that are so different from her own character? What might the poet be suggesting, through this difference?
Answer:
Aunt Jennifer is old and submissive woman. But the tigers she is embroidering on the panel appear to be bold and chivalric. The suggestion given here is that women give birth to men but the same men tyrannise women when they grow up.

Question 17.
Interpret the symbols found in this poem.
Answer:
The poet has used the symbol of tigers in this poem. The tigers represent creative energy of women. The tigers also represent the male-dominant society. The poet wants to say that the women give birth to men, but the same men tyrannise women when they grow up.

Question 18.
Do you sympathise with Aunt Jennifer ? What is the attitude of the speaker towards Aunt Jennifer ?
Answer:
Yes, we do sympathise with Aunt Jennifer. Aunt Jennifer symbolises particular housewife. She has to do all the household chores without any respite. Her husband is very cruel and often tyrannises her. The poet says that perhaps Aunt Jennifer will have to continue with her household chores even after death.

Question 19.
For Aunt Jennifer what do the tigers symbolise ?
Answer:
The tigers symbolise creative energy of women. The tigers also represent the male-dominant society. The poet wants to say that the women give birth to men, but the same men tyrannise women when they grow up.

Question 20.
What will happen to Aunt Jennifer’s tigers when she is dead ?
Answer:
Aunt Jennifer has embroidered tigers on a panel. These tigers represent not only women’s creativity but also tyranny of men towards women. It will continue even after the death of Aunt Jennifer. Therefore her tigers will also keep prancing on the panel.

Question 21.
Why did Aunt Jennifer choose to embroider tigers on the panel ?
Answer:
Aunt Jennifer has been tyrannised by her husband all her life. Her husband has become a picture of terror for her. She is in fact venting out all her inner feelings by embroidering tigers on the panel. In the form of tigers she has in fact embroidered the fearful face of her husband.

Question 22.
Aunt Jennifer’s efforts to get rid of her fear proved to be futile. Comment.
Answer:
Aunt Jennifer embroidered tigers on the screen. These tigers are symbol of her husband, whom she is very afraid. She thinks that by embroidering tigers she will get a sort of relief from her fear. But it proves quite futile. The poet says that even after her death, the fear of her husband’s tyranny will keep on haunting Aunt Jennifer.

Question 23.
Why does Aunt Jennifer create animals that are so different from her own character ?
Answer:
Aunt Jennifer is old and submissive woman. But the tigers she is embroidering on the panel appear to be bold and chivalric. The suggestion given here is that women give birth to men but the same men tyrannise women when they grow up.

Question 24.
What picture of male chauvinism (tyranny) do we find in the poem, ‘Aunt Jennifer’s Tigers’?
Answer:
Ours is a male-dominated society. Aunt Jennifer is a typical housewife. She has to follow her husband’s orders slavishly. Her husband tyrannises her and she has accepted her fate submissively. In fact this poem reflects a true picture of male chauvinism.

Aunt Jennifer’s Tigers Extra Questions and Answers Long Answer Type

Question 1.
Write in brief the summary of the poem.
Answer:
The poet refers to an old woman, Aunt Jennifer. She has embroidered some tigers on a screen. These tigers are jumping across the screen. The poet says that these tigers appear so real as if they were actually the inhabitants of the jungle. Some men are shown beneath the tree. But these tigers are fear¬less. They are not afraid of these men. Aunt Jennifer has become so old that it appears that her fin¬gers are trembling through wool. She has become so weak that she even finds the needle hard to pull.

The poet says that the uncle wedding band lies very heavily on Aunt Jennifer’s hand. The poet means to say here that Aunt Jennifer has to slavishly follow all the orders of uncle. Aunt Jennifer is terrified of endless household chores and Uncle. She thinks that even after her death she will not be free from these household chores.

Question 2.
Write in brief the central idea of the poem.
Answer:
In this poem the poet narrates the tale of an old woman Aunt Jennifer. She is a typical housewife. She is embroidering tigers on a frame. Aunt Jenni-fer has suffered all her life because of male-dominance. The tigers she is embroidering are in fact symbol of her husband. They can also be seen as a symbol of a woman’s creative energy. The women give birth to men and the same men tyrannise women when they grow up. The poet says that Aunt is crushed due to male chauvinism and it appears she won’t be free from the bondage of her household chores even after her death.

In this page you can find A Roadside Stand Extra Questions and Answers Class 12 English Flamingo, Extra Questions for Class 12 English will make your practice complete.

A Roadside Stand Extra Questions and Answers Class 12 English Flamingo

A Roadside Stand Extra Questions and Answers Short Answer Type

Question 1.
Why does the poet refer to the roadside stand as pathetic?
Answer:
The poet refers to the roadside stand as pathetic because it looked awkward and unattractive to the eye. Naturally, it failed to attract the sophisticated city people who drove past, without even a second glance.

Question 2.
Who do these pitiful kin refer to? Why will they be mercifully gathered in?
Answer:
These pitiful kin refers to the villagers who have been deprived of their home and land. They will be mercifully gathered in to live in villages near the theatre and the stores.

Question 3.
What is the party in power keeping from these rural poor?
Answer:
The government, and the civic authorities who appear to help them but actually end up harming them are relocating them to the vicinity of the towns near the theatre and the shops which is a great disservice to the people. They will be thus, robbed of their voices and their freedom and ability to find solutions to their problems.

Question 4.
What is the childish longing that the poet refers to? Why is it vain?
Answer:
Childish longing seems to emanate from the roadside shed, for a life that is described in ‘ the movies, a life so far removed from their life in the village. The thoughtless occupants of a car who stop at the shed to buy a gallon of gas, speaks of the disconnect that exists in the perceptions of town people with regard to the villagers.

Question 5.
What does the poet wish he could do for these people? Why does he change his mind?
Answer:
The poem is an expression of the rage that the poet feels on behalf of the farmers, with whom his sympathies lie. Enraged, the poet wishes he could put the farmers out of their pain at one stroke. However, he immediately checks himself and wonders how he would react if someone offered to do the same to him.

Question 6.
What kind of support do the country folks expect to receive from city dwellers?
Answer:
The country folks starved of cash, look for financial support and patronage from city dwellers. They feel that if they could have some cash with them, then they could lead a much better and prosperous life.

Question 7.
How does the poet criticise the city ways?
Answer:
According to the poet, the city folks are mean and selfish. They refuse to extend any kind of support to the rural poor. Although they are rich, yet they are very possessive about their money. The city folks are so carried by their lifestyle that they have no time to stand and appreciate the nature’s beauty. They show no compassion and concern for the poor villagers.

Question 8.
What empty promises are made to the country people?
Answer:
The people in power use the media to assure the country folks that they would be soon pulled out of their poverty. Such tall promises turn out to be false as they are never fulfilled.

Question 9.
Give examples of contrast and irony in the poem.
Answer:
The use of expressions ‘greedy good-doers’ and ‘beneficent beasts of prey’ bring out the use of irony and contrast by the poet.

Question 10.
What is the ‘open prayer’ made by the country folks?
Answer:
The people in the rural areas make an open appeal to the people of the city. The rural folks pray that they should not be so selfish. Instead, they should stop at the roadside stand and help them lead a better life.

Question 11.
State the reasons for which the cars from the city halt at the roadside stand.
Answer:
The people from the city halt their cars at times to plough the grass and use the yard to back and turn around. Sometimes, they stop to ask for the right way and path. At times, they stop to enquire about a gallon of gas.

A Roadside Stand Extra Questions and Answers Long Answer Type

Question 1.
Write in brief the summary of the poem.
Answer:
Poet, Robert Frost experienced the pain of the poor formers who established their little shedded stalls to sell various products grown or manufactured by them but the poet observed that out of thousands of the visitors and vehicles, nobody is interested in their offerings. On the other hand, the selfish travellers criticized their presentations and passed throughly proudly.

Poet is hurt by their behaviour and attitude and has a complaint for their survival as they too want to be the part of the flow of economy; presently mainly run by the city dwellers only. They too have the right to live comfortably like their ideals. But they are always used for the self motives of the greedy good-doers. They enforce their benefits over the poor farmers, misguide them and destroy their ancient

culture and way of living by lullying them. They just want to grasp their fields and houses. Poet is tired and finds his expectations failed, too much disappointed by the financial condition and struggle V of the distressed peasants who for whole day sit, pray and wait for the cars to stop at least to inquire or to buy but the self-centred egoistic persons use the empty place to turn their vehicles or sometimes stop to ask about the path or fuel.

Anger of farmers is natural, they reply and ask’ irritatingly for the common sense of the proudy persons. Poet realizes that no miracle can be seen and he is unable to console the poverty-stricken farmers and it’s impossible to extricate the villagers out of their pain at one stroke. He realizes, when finds himself sensible, that his call is futile, to help them and no one is ready to help them.

Question 2.
Have you ever stopped at a roadside stand ? What have you observed ?
Answer:
Yes, I’ve stopped at a roadside stand on a highway twice or thrice and found that the villagers have too much expectations from us, who pass from those roads. They work hard for whole day and whole family members of them sit there to sell fresh vegetables, fruits, juices and other products.

Very few of us actually purchase something but only use them for general queries like asking about road map, gas or petrol for our vehicles or many a times to use that broad empty space to turn our vehicles. I also observed that those farmers are pitiful and facing very miserable condition and fighting for their existence and survival.

Those merciful poor farmers should be helped and treated like the human beings and dwellers of cities. They should not be cheated and used for the introversion purposes. They also contribute to the growth and economy of the country as they grow crops for whole mankind.

Question 3.
Which lines tell us about the insufferable pain that the poet feels at the throught of the plight of the rural people?
Answer:
The lines about the insufferable pain that the poet feels are :
“Sometimes I feel myself I can hardly bear the thought of so much Childish longing in vain, the sadness that lurks near the open window there.” “I can’t help owning the great relief it would be to put these people at one stroke out of their pain.”

Solved the very best collection of Chemical Reactions and Equations Class 10 Science Important Questions and Answers Chapter 1 Pdf from the latest NCERT edition books, It will help you in scoring more marks in CBSE Exams.

Chemical Reactions and Equations Class 10 Important Questions with Answers Science Chapter 1

Chemical Reactions and Equations Class 10 Important Questions Very Short Answer Type

Question 1.
State one basic difference between a physical change and a chemical change   (CBSE 2011)
Answer:
In physical change, no new substance is formed, whereas in a chemical change, new substance(s) is/are formed.

Question 2.
What is meant by a chemical reaction?   (CBSE 2011)
Answer:
The reaction representing a chemical change is called a chemical reaction.

Question 3.
Hydrogen being a highly inflammable gas and oxygen being a supporter of combustion, yet water which is a compound made up of hydrogen and oxygen is used to extinguish fire. Why?   (CBSE 2011)
Answer:
It is because properties of compound (H₂O) are different from properties of its constituting elements, i.e., H₂ and O₂.

Chemical Reactions and Equations Class 10 Important Questions Short Answer Type

Question 1.
What happens chemically when quick lime is added to water?   (CBSE 2008)
Answer:
Quick lime is CaO. On adding water to it, combination reaction takes place to give calcium hydroxide with release of large amount of heat.
CaO + H₂O → Ca(OH)₂

Question 2.
How will you test for the gas which is liberated when hydrochloric acid reacts with an active metal?   (CBSE 2008)
Answer:
The gas liberated is hydrogen and it can be tested by taking a burning matchstick near the mouth of the test tube in which reaction is taking place. The matchstick will burn with a pop sound.

Question 3.
What is an oxidation reaction? Identify in the following reactions:
(i) the substance oxidized and
(ii) the substance reduced.
ZnO + C → Zn + CO   (CBSE 2008)
Answer:
The reaction in which a substance loses hydrogen or gains oxygen is called oxidation reaction. In the given reaction C is oxidized as it gains oxygen and ZnO is reduced as it loses oxygen.

Question 4.
Give an example of photochemical reaction.  (CBSE 2008)
Answer:
In black and white photography AgBr gets decomposed due to light and forms silver metal and bromine gas.

Question 5.
Give an example of a decomposition reaction. Describe an activity to illustrate such a reaction by heating.  (AI 2008)
Answer:
Example of decomposition reaction:
\(\mathrm{CaCO}_{3} \stackrel{\text { heat }}{\longrightarrow} \mathrm{CaO}+\mathrm{CO}_{2}\)
Activity:
Take a test tube add CaCO₃ in it and heat. CO₂ gas is evolved leaving behind CaO as solid. Allow the gas to pass through lime water which turns milky and confirms CO₂ gas.

Question 6.
Balance the following chemical equation:
Fe(s) + H₂O(g) → Fe₃O₄(s) + H₂(g)   (AI 2008)
Answer:
3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)

Question 7.
Why is respiration considered as an exothermic process?   (AI 2008)
Answer:
During respiration heat is released so it is termed as an exothermic reaction.
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy

Question 8.
Balance the following chemical equation:    (AI 2008C)
\(\mathrm{FeSO}_{4} \stackrel{\text { heat }}{\longrightarrow} \mathrm{Fe}_{2} \mathrm{O}_{3}+\mathrm{SO}_{2}+\mathrm{SO}_{3}\)
Answer:
\(2 \mathrm{FeSO}_{4} \stackrel{\text { heat }}{\longrightarrow} \mathrm{Fe}_{2} \mathrm{O}_{3}+\mathrm{SO}_{2}+\mathrm{SO}_{3}\)

Question 9.
Balance the following chemical equation:
MnO₂ + HCl → MnCl₂ + Cl₂ + H₂O   (AI 2008)
Answer:
MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O

Question 10.
On what basis is a chemical equation balanced?   (Foreign 2008)
Answer:
The number of atoms on left hand side of the reaction (i.e., reactants) is equal to the number of atoms on the right hand side of the equation (i.e., product).
Law of Conservation of Mass: Mass of atoms in chemical reaction can neither be created nor be destroyed, it remains the same.

Question 11.
State any two observations in an activity, which may suggest that a chemical reaction has taken place. Given examples to support your answer.   (Foreign 2008)
Answer:
The following observations in an activity may suggest that a chemical reaction has taken place:

• Change in state
• Change in colour
• Formation of a precipitate
• Evolution of a gas
• Change in temperature

Question 12.
Identify the type of reaction in the following example:
Na₂SO₄(aq) + BaCl₂(aq) → BaSO₄(s) + 2NaCl(aq)     (CBSE 2008C)
Answer:
It is a double displacement reaction.

Question 13.
Identify the type of reaction in the following example:
Fe(s) + CuSO₄ (aq) → FeSO₄(aq) + Cu(s)   (CBSE 2008C)
Answer:
It is a displacement reaction. Fe displaces Cu from CuSO₄.

Question 14.
Identify the type of reaction in the following example:
2H₂(g) + O₂(g) → 2H₂O(g)   (CBSE 2008C)
Answer:
It is a combination reaction.

Question 15.
Balance the given chemical equation:   (AI 2008C)
HNO₃ + Ca(OH)₂ → Ca(NO₃)₂ + H₂O
Answer:
2HNO₃ + Ca(OH)₂ → Ca(NO₃)₂ + 2H₂O

Question 16.
Balance the given chemical equation:   (AI 2008C)
Al(s) + CuCl₂(aq) → AlCl₃(aq) + Cu(s)
Answer:
2Al(s) + 3CuCl₂(aq) → 2AlCl₃(aq) + 3Cu(s).

Question 17.
Balance the following chemical equation:
\(\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{s}) \stackrel{\text { heat }}{\longrightarrow} \mathrm{PbO}(\mathrm{s})+\mathrm{NO}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g})\)    (CBSE 2009)
Answer:
\(2 \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2} \stackrel{\text { heat }}{\longrightarrow} 2 \mathrm{PbO}(\mathrm{s})+4 \mathrm{NO}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g})\)

Question 18.
Name a reducing agent that may be used to obtain manganese from manganese dioxide.   (CBSE 2009)
Answer:
Coke or carbon is used as reducing agent.

Question 19.
In electrolysis of water, why is volume of gas collected over one electrode double that of gas collected over the other electrode?   (AI 2009)
Answer:
The volume of gas collected over one electrode is double than that of the gas collected over the other electrode as the ratio of H : O in water is 2 : 1.

Question 20.
What change in colour is observed when silver chloride is left exposed to sunlight?
What type of chemical reaction is this?   (Foreign 2009)
Answer:
Silver turns black, the reaction is decomposition.

Question 21.
How can we know whether a reaction has taken place or not?   (Delhi 2010)
Answer:
The following observations in an activity may suggest that a chemical reaction has taken place:

• Change in state
• Change in colour
• Formation of precipitate
• Evolution of a gas
• Change in temperature

Question 22.
Define a combination reaction. Give one example of a combination reaction which is also exothermic.   (CBSE 2009)
Answer:
Combination reaction: It is a reaction in which two elements or compounds combine together to form a product.
e.g

Question 23.
Using a suitable chemical equation, justify that some chemical reactions are determined by:
(i) change in colour,
(ii) change in temperature.   (CBSE 2011)
Answer:

Question 24.
(a) A solution of substance ‘X’ is used for white washing. What is the substance ‘X’? State the chemical reaction of ‘X’ with water.
(b) Why does the colour of copper sulphate solution change when an iron nail is dipped in it?   (CBSE 2011)
Answer:
(a) ‘X’ is calcium oxide (CaO).
CaO(s) + H₂O(l) → Ca(OH)₂(aq) + heat
(b) It is because iron displaces copper from CuS04 to form FeS04 which is pale green.
\(\mathrm{Fe}(\mathrm{s})+\underset{\text { Blue }}{\mathrm{CuSO}_{4}}(\mathrm{aq}) \longrightarrow \underset{\text { Pale green }}{\mathrm{FeSO}_{4}(\mathrm{aq})}+\mathrm{Cu}(\mathrm{s})\)

Question 25.
Balance the following chemical equations.
(i) BaCl₂ + H₂SO₄ → BaSO₄ + HCl
(ii) Ca(OH)₂ + HNO₃ → Ca(NO₃)₂ + H₂O
(iii) Pb(NO₃)₂ → PbO + NO₂ + O₂
(iv) MnO₂ + HCl → MnCl₂ + H₂O + Cl₂   (CBSE 2011)
Answer:
(i) BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl
(ii) Ca(OH)₂ + 2HNO₃ → Ca(NO₃)₂ + 2H₂O
(iii) 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂
(iv) MnO₂ + 4HC1 → MnCl₂ + 2H₂O + Cl₂

Question 26.
Write the balanced equation for the following reaction and identify the type of reaction in each case.
(i) Potassium bromide + Barium iodide → Potassium iodide + Barium bromide.
(ii) Hydrogen(g) + Chlorine(g) → Hydrogen chloride(g)   (CBSE 2011)
Answer:
(i) 2KBr(aq) + BaI₂(aq) → 2KI(aq) + BaBr₂(aq)
It is a double displacement reaction.
(ii) H₂(g) + Cl₂(g) → 2HCl(g)
It is a combination reaction.

Question 27.
A zinc plate was put into a solution of copper sulphate kept in a glass container. It was found that blue colour of the solution gets fader and fader with the passage of time. After few days, when zinc plate was taken out of the solution, a number of holes were observed on it.
(i) State the reason for changes observed on the zinc plate.
(ii) Write the chemical equation for the reaction involved.   (CBSE 2011)
Answer:
(i) It is because zinc has displaced copper from CuSO₄. Zinc metal has been used to form zinc sulphate, therefore, number of holes were observed.
(ii) \(\mathrm{Zn}(\mathrm{s})+\underset{\text { Blue }}{\mathrm{CuSO}_{4}}(\mathrm{aq}) \longrightarrow \underset{\text { Colourless }}{\mathrm{ZnSO}_{4}}(\mathrm{aq})+\mathrm{Cu}(\mathrm{s})\)

Question 28.
A white salt on heating decomposes to give brown fumes and a residue is left behind.
(i) Name the salt.
(ii) Write the equation for the decomposition reaction.    (CBSE 2011)
Answer:
(i) Lead nitrate is white salt.
(ii) \(2 \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{s}) \stackrel{\text { Heat }}{\longrightarrow} 2 \mathrm{PbO}(\mathrm{s})+4 \mathrm{NO}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g})\)

Question 29.
When a solution of potassium iodide is added to a solution of lead nitrate in a test tube, a reaction takes place.
(a) What type of reaction is this?
(b) Write a balanced chemical equation to represent the above reaction.   (CBSE 2011)
Answer:
Double displacement as well as precipitation reaction.
(a) Double displacement as well as precipitation reaction.
(b) \(\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+2 \mathrm{KI}(\mathrm{as}) \longrightarrow \underset{\text { Yellow ppt. }}{\mathrm{PbI}_{2}(\mathrm{s})}+2 \mathrm{KNO}_{3}(\mathrm{aq})\)

Question 30.
Define combination reaction. Give one example of a combination reaction which is also exothermic.   (CBSE 2011)
Answer:
A reaction in which two or more elements or compounds combine to form a single compound is called combination reaction.
CaO(s) + H₂O(l) → Ca(OH)₂(aq) + heat
It is also an exothermic reaction along with a combination reaction because heat is evolved.

Question 31.
(a) Classify the following reactions into different types.
(i) AgNO₃(aq) + NaCl(aq) → AgCl(s) + NaNO₃(aq)
(ii) CaO(s) + H₂O(l) → Ca(OH)₂(aq)
(iii) 2KClO₃(S) → 2KCl(aq) + 3O₂(g)
(b) Which of the above reaction(.s) is/are precipitation reaction(s)? Why is a reaction called precipitation reaction? (CBSE 2011)
Answer:
(a) (i) Precipitation reaction (Double displacement reaction)
(ii) Combination reaction
(iii) Decomposition reaction
(b) Reaction (i) is a precipitation reaction because one of the product formed is insoluble in water.

Question 32.
Write balanced equations for the following mentioning the type of reaction involved.
(i) Aluminium + Bromine → Aluminium bromide
(ii) Calcium carbon → Calcium oxide + Carbon dioxide
(iii) Silver chloride → Silver + Chlorine    (CBSE 2011)
Answer:
(i) 2Al(s) + 3Br₂(g) → 2AlBr₃(s)
(ii) CaCO₃(s) → CaO(s) + CO₂(g)
(in) \(2 \mathrm{AgCl}(\mathrm{s}) \stackrel{\text { Sunlight }}{\longrightarrow} 2 \mathrm{Ag}(\mathrm{s})+\mathrm{Cl}_{2}(\mathrm{g})\)

Question 33.
(a) Why is respiration considered as an exothermic reaction?
(b) Define the terms oxidation and reduction.
(c) Identify the substance that is oxidised and reduced in the following reaction.
CuO(s) + Zn(s) → Cu(s) + ZnO(s)     (CBSE 2011)
Answer:
(a) It is because heat is evolved during respiration.
(c) Zn is getting oxidised, CuO is getting reduced.

Question 34.
What is meant by
(i) precipitation reaction,
(ii) exothermic reaction,
(iii) oxidation reaction?
Write balanced chemical equations for an example of each.       (CBSE 2011)
Answer:
(i) Precipitation reaction: The reaction in which two compounds exchange their ions and the product formed is insoluble in water is called precipitation reaction.
AgNO₃(aq) + KI(aq) → Agl(s) + KNO₃(aq)
(ii) Exothermic reaction: The reaction in which heat is evolved is known as exothermic reaction.
C + O₂ → CO₂ + heat
(iii) Oxidation reaction: The reaction in which O₂ is added or H₂ is removed or loss of electrons takes place is called oxidation reaction.
2Cu + O₂ → 2CuO

Question 35.
You might have noted that when copper powder is heated in a china dish, the surface of copper powder becomes coated with a black colour substance.
(i) How has this black coloured substance formed?
(ii) What is that black substance?
(iii) Write the chemical equation of the reaction that takes place.     (CBSE 2011)
Answer:
(i) Copper reacts with oxygen to form copper oxide which is black, i.e., oxidation of copper takes place
(ii) Copper oxide
(iii) 2Cu(s) + O₂(g) → 2CuO(s)

Question 36.
Write balanced chemical equations for the following reactions.
(i) Silver bromide on exposure to sunlight decomposes into silver and bromine,
(ii) Sodium metal reacts with water to form sodium hydroxide and hydrogen gas.     (CBSE 2012)
Answer:

Question 37.
Identify the type of reactions(s) in the following equations.
(i) CH₄ + 2O₂ → CO₂ + 2H₂O
(ii) Pb(NO₃)₂ + 2Kl → Pbl₂ + 2KNO₃
(iii) CaO + H₂O → Ca(OH)₂
(vi) CuSO₄ + Zn → ZnSO₄ + Cu     (CBSE 2012)
Answer:
(i) Combustion reaction and oxidation reaction.
(ii) Double displacement reaction and precipitation reaction.
(iii) Combination reaction.
(iv) Displacement reaction.

Question 38.
Write balanced equation for the reaction between magnesium and hydrochloric acid. Name the product obtained, identify the type of reaction. (CBSE 2012)
Answer:
Mg(s) + 2HCl(dil.) → MgCl₂(aq) + H₂(g)
The product formed is magnesium chloride and hydrogen gas.
It is a displacement reaction.

Question 39.
Describe an activity to observe what happens when quicklime is added to water taken in a beaker. State two important observations and name the type of reaction taking place.   (CBSE 2012)
Answer:
Aim: To observe what happens when quicklime is added to water taken in a beaker.
Materials Required: Quicklime (calcium oxide), water, beaker.
Procedure:
1. Take 5g of calcium oxide in a beaker.
2. Add water to it slowly.
3. Touch the beaker.
4. Note down the observations.

Observation:
Calcium oxide reacts with water vigorously to form calcium hydroxide with the evolution of heat.
Chemical Reaction:

Conclusion:
The reaction between CaO (calcium oxide) and H₂O is a combination reaction. It is an exothermic process because heat is evolved.

Question 40.
What is the colour of ferrous sulphate crystals? How does this colour change after heating?   (CBSE 2012)
Answer:
The colour of ferrous sulphate is pale green. The colour changes to reddish brown on heating due to formation of iron (III) oxide.

Question 41.
Why does the colour of copper sulphate solution change when an iron nail is dipped in it? Write two observations. (CBSE 2012)
It is because displacement reaction takes place. Iron displaces copper from copper sulphate solution and forms pale green colured solution of FeSO₄ and reddish brown copper metal gets deposited.
Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s)

Question 42.
Translate the following statement into chemical equation and then balance it. Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate. State the two types in which this reaction can be classified.   (CBSE 2012)
Answer:
3BaCl₂(aq) + Al₂(SO₄)₃(aq) → 3BaSO₄(s) + 2AlCl₃(aq)
It can be classified as double displacement as well as precipitation reaction.

Question 43.
Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions. (CBSE 2012)

Question 44.

The following diagram displays a chemical reaction.
Observe carefully and answer the following questions
(a) Identify the type of chemical reaction that will take place and define it. How will the colour of the salt change?
(b) Write the chemical equation of the reaction that takes place.
(c) Mention one commercial use of this salt.   (CBSE 2012)
Answer:
(a) Photochemical decomposition reaction: Those reactions in which a compound breaks down into simple substances in presence of light are called photochemical decomposition reaction. The colour of salt will change from white to grey.
(b) \(2 \mathrm{AgCl}(\mathrm{s}) \stackrel{\text { Sunlight }}{\longrightarrow} 2 \mathrm{Ag}(\mathrm{s})+\mathrm{Cl}_{2}(\mathrm{g})\)
(c) Silver chloride is used in photography.

Question 45.
What is rancidity? Mention any two ways by which rancidity can be prevented.   (CBSE 2012)
Answer:
The process in which taste and smell of food containing oils or fats gets spoiled is called rancidity. It happens due to oxidation.

Prevention from rancidity:

1. Antioxidants are added to fatty acids to prevent oxidation, e.g., chips are packed in presence of nitrogen gas which prevents spoilage by oxidation.
2. Food should be kept in airtight container in refrigerator.

Question 46.
Write balanced chemical equation for the reactions that take place during respiration. Identify the type of combination reaction that takes place during this process and justify the name. Give one more example of this type of reaction.    (CBSE 2012)
Answer:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + heat
It is an exothermic combination reaction because heat is evolved.
CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O
Combustion of methane is another example of exothermic combination reaction.

Question 47.
What is redox reaction? Identify the substance oxidised and the substance reduced in the following reactions.
(i) 2PbO + C → 2Pb + CO₂
(ii) MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂    (CBSE 2012)
Answer:
Those reactions in which oxidation and reduction takes place simultaneously are called redox reactions.
(i) PbO getting reduced and C is getting oxidsed.
(ii) MnO₂ is getting reduced and HCl is getting oxidised.

Question 48.
Write the balanced chemical equations for the following reactions and identify the type of reaction in each case.
Thermite reaction, iron (III) oxide reacts with aluminium and gives molten iron and aluminium oxide  (CBSE 2012)
Answer:

It is a displacement reaction because aluminium is more reactive then iron and displaces it. The iron melted in here is used in joining the railway tracks.

Question 49.
Which products will be obtained when lead nitrate is heated simply. Write balanced chemical equation for the reaction. State the type of chemical reaction that occur in the change.     (CBSE 2013)
Answer:
Lead monoxide, nitrogen dioxide and oxygen gas will be liberated.
\(2 \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{s}) \stackrel{\text { heat }}{\longrightarrow} 2 \mathrm{PbO}(\mathrm{s})+4 \mathrm{NO}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g})\)
It is thermal decomposition reaction.

Question 50.
What is meant by skeletal type chemical equation? What does it represent? Using the equation for electrolytic decomposition of water, differentiate between a skeletal chemical equation and a balanced chemical equation. (CBSE 2013)
Answer:
The equation in which reactants and products formed are shown by their chemical formulae without considering the balancing of atoms is called skeletal type equation. It represents the reactants and products that are involved in the reaction.
H₂O → H₂ + O₂ (skeletal equation)
2H₂O → 2H₂ + O₂ (Balanced chemical equation)

Question 51.
What is observed when a solution of potassium iodide solution is added to a solution of lead nitrate? Name the type of reaction. Write a balanced chemical equation to represent the above chemical reaction.    (CBSE 2014)
Answer:
Yellow precipitate of lead iodide is formed. It is a precipitation reaction.
Pb(NO₃)₂(aq) + 2KI(aq) → PbI₂(s) + 2KNO₃(aq)
It is also called double displacement reaction.

Question 52.
Write chemical equation of reactions taking place when carried out with the help of
(a) Iron reacts with steam
(b) Magnesium reacts with dil HCl
(c) Copper is heated in air.     (CBSE 2014)
Answer:
(a) 3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)
(b) Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)
(c) \(2 \mathrm{Cu}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) \stackrel{\text { heat }}{\longrightarrow} 2 \mathrm{CuO}(\mathrm{s})\)

Question 53.
“We need to balance a skeletal chemical equation.” Give reason to justify the statement.    (CBSE 2015)
Answer:
Skeletal chemical equations are unbalanced. We need to balance chemical equation because of law of conservation of mass. It states that ‘matter can neither be created nor be destroyed’. Therefore, each and every atom involved in chemical equation must be balanced.

Question 54.
Giving an example list two information which make a chemical equation more useful (informative)     (CBSE 2015)
Answer:
(i) Physical state of reactants must be mentioned, e.g.,
2H₂(g) + O₂(g) → 2H₂O(l)
(ii) Condition in which reaction takes place are written on the arrow head, e.g.,

Question 55.
Consider the following chemical reaction
X + Barium chloride → Y + Sodium chloride
(a) Identify ‘X’ and ‘Y
(b) The type of reaction (CBSE 2015)
Answer:
(a) ‘X’ is Na₂SO₄ and Y is BaSO₄
(b) The type of reaction
Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl
(White ppt)
The reaction is precipitation reaction. It is also a double displacement reaction

Question 56.
Name the reducing agent from the following reaction:
3MnO₂ + 4Al → 3Mn + 2Al₂O₃
State which is more reactive, Mn or Al and why?     (CBSE 2015)
Answer:
‘Al’ is more reactive than Mn as ‘Al’ displaces Mn from its oxide.

Question 57.
(i) Write a balanced chemical equation for process of photosynthesis.
(ii) When do desert plants take up carbon dioxide and perform photosynthesis?        (CBSE 2015)
Answer:
(I) \(6 \mathrm{CO}_{2}(\mathrm{g})+6 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \stackrel{\text { Sunlight }}{\longrightarrow} \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(\mathrm{s})+6 \mathrm{O}_{2}(\mathrm{g})\)
(ii) In desert plants the stomata are open at night. They take CO₂ at night and is
stored in the from of acid and is used during day time for photosynthesis.

Question 58.
Name the type of chemical reaction represented by the following equation:
(i) CaO + H₂O → Ca(OH)₂
(ii) 3BaCl₂ + Al₂(SO₂)₃ → 3BaSO₄ + 2AlCl₃
(iii) 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃          (CBSE 2015)
Answer:
(i) Combination reaction
(ii) Double displacement reaction (Precipitation reaction)
(iii) Decomposition reaction.

Question 59.
Write the chemical equation of the reaction in which the following changes have taken place with an example of each:
(i) Change in colour
(ii) Change in temperature
(iii) Formation of precipitate    (CBSE 2015)
Answer:
(i) Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq) + 2Ag(s)
The solution will become blue in colour and shiny silver metal will be deposited.
(ii) NaOH + HCl → NaCl + H₂O + heat
The temperature will increase because heat will be evolved.
(iii) Pb(NO₃)₂(aq) + 2KI(aq) → Pbl₂(s) + 2KNO₃(aq)
Yellow precipitate of Pbl₂ will be formed

Question 60.
State the type of chemical reactions and chemical equations that take place in the following:
(i) Magnesium wire is burnt in air.
(ii) Electric current is passed through water,
(iii) Ammonia and hydrogen chloride gases are mixed.     (CBSE 2015)
Answer:
(i) 2Mg(s) + O₂(g) → 2MgO(s)
Combination reaction (Redox reaction).
(ii) \(2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \stackrel{\text { electrolysis }}{\longrightarrow} 2 \mathrm{H}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g})\)
Electrical decomposition reaction.
(iii) NH₃(g) + HCl(g) → NH₄Cl(s)
Combination reaction.

Question 61.
(a) Write the essential condition for the following reaction to take place:
2AgBr → 2Ag + Br₂
Write one application of this reaction.
(b) Complete the following chemical equation
\(2 \mathrm{FeSO}_{4} \longrightarrow \stackrel{\Delta}{\longrightarrow} \mathrm{Fe}_{2} \mathrm{O}_{3}+\ldots+\ldots\)
(c) What happens when water is added to quick lime? Write chemical equation. (CBSE 2015)
Answer:
(a) \(2 \mathrm{AgBr} \stackrel{\text { Sunlight }}{\longrightarrow} 2 \mathrm{Ag}+\mathrm{Br}_{2}\)
This reaction used in photography
(b) \(2 \mathrm{FeSO}_{4} \stackrel{\text { heat }}{\longrightarrow} \mathrm{Fe}_{2} \mathrm{O}_{3}+\mathrm{SO}_{2}+\mathrm{SO}_{3}\)
(c) Slacked lime is formed with hissing sound and lot of heat is envolved

Question 62.
2g of ferrous sulphate crystals are heated in a dry boiling tube.
(i) List any two observations
(ii) Name the type of chemical reaction taking place.
(iii) Write the chemical equation for the reaction. (CBSE 2015)
Answer:
(i) Green colour of FeSO₄ disappears and reddish brown solid is formed.
Smell of burning sulphur.
(ii) Decomposition reaction
(iii) \(2 \mathrm{FeSO}_{4}(\mathrm{s}) \stackrel{\text { heat }}{\longrightarrow} \mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{s})+\mathrm{SO}_{2}(\mathrm{g})+\mathrm{SO}_{3}(\mathrm{g})\)

Chemical Reactions and Equations Class 10 Important Questions Long Answer Type

Question 1.
Solid calcium oxide was taken in a container and water was added slowly to it.    (AI 2008C)

(i) State the two observations made in the experiment.
(ii) Write the name and chemical formula of the product formed.
Answer:
(i) Calcium oxide reacts vigorously with water to produce slaked lime and large amount of heat is released.

Question 2.
What is an oxidation reaction? Give an example of oxidation reaction. Is oxidation an exothermic or an endothermic reaction? (CBSE 2009)
Answer:
The reaction in which oxygen is added or hydrogen is removed is called oxidation reaction.
\(\text { e.g., } 2 \mathrm{Cu}+\mathrm{O}_{2} \stackrel{\text { heat }}{\longrightarrow} 2 \mathrm{CuO}\)
It is an endothermic reaction.

Question 3.
(i) What is observed when a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube?
(ii) What type of reaction is this?
(iii) Write a balanced chemical equation to represent the above reaction.     (AI 2009)
Answer:
(i) Yellow coloured precipitate is formed due to formation of lead iodide.
(ii) It is a double displacement reaction.
(iii) 2KI + Pb(NO₃)₂ → 2KNO₃ + Pbl₂

Question 4.
Distinguish between an exothermic and an endothermic reaction. Amongst the following reactions, identify the exothermic and the endothermic reaction.
(i) Heating coal in air to form carbon dioxide.
(ii) Heating lime-stone in a lime kiln to form quick lime.       (Foreign 2009)
Answer:

Exothermic Reaction	Endothermic Reaction
The reaction in which heat is released.	The reaction in which heat is absorbed.

(i) Exothermic
(ii) Endothermic

Question 5.
Distinguish between a displacement reaction and a double displacement reaction. Identify the displacement and the double displacement reaction from the following reactions.
(i) HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
(ii) Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s)     (Foreign 2009)
Answer:

Displacement Reaction	Double Displacement Reaction
The reaction in which more reactive metal displaces less reactive metal.	The reaction in which two different atoms or group of atoms exchange for each other.

(i) It is a double displacement reaction.
(ii) It is a displacement reaction.

Question 6.
(a) Write one example for each of decomposition reaction carried out with help of
(i) Electricity
(ii) Heat
(iii) Light
(b) Which of the following statements is correct and why copper can displace silver from silver nitrate and silver can displace copper from copper sulphate solution.        (CBSE 2014)
Answer:

(b) Copper can displace silver from AgN03 because copper is more reactive than Ag
Cu + 2AgNO₃(ag) → Cu(NO₃)₂(aq) + 2Ag(s)

Question 7.
(a) Define a balanced chemical equation. Why should an equation be balanced?
(b) Write the balanced chemical equation for the following reaction:
(i) Phosphorus burns in presence of chlorine to form phosphorus pentachloride.
(ii) Burning of natural gas.
(iii) The process of respiration.      (CBSE 2015)
Answer:
(a) Balanced chemical equation has an equal number of atoms of different elements in the reactants and products. According to law of conservation of mass, matter can neither be created nor be destroyed in a chemical reaction.
(b) (i) P₄(s) + 10Cl₂(g) → 4PCl₅(S)
(ii) CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g) + heat energy
(iii) C₆H₁₂O₆(S) + 6O₂(g) → 6CO₂(aq) + 6H₂O(l) + energy

Question 8.
(a) Explain two ways by which food industries prevent rancidity.
(b) Discuss the importance of decompostion reaction in metal industry with three points. (CBSE 2015)
Answer:
(a) (i) Rancidity can be prevented by adding antioxidants to food containing fat and oil, e.g., butylated hydroxyanisole is added to butter as antioxidant
(ii) It can be prevented by packaging fat and oil containing foods in nitrogen gas.

(b) (i) Molten NaCl is electrolytically decomposed to form sodium metal.
(ii) Aluminium metal is obtained by electric decomposition of bauxite ore mixed with cryolite.
(iii) Carbonate ores are thermally decomposed to give metal oxide which on reduction give metal.