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

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Class 10 Science Chapter 4 Extra Questions and Answers Carbon and its Compounds

Extra Questions for Class 10 Science Chapter 4 Carbon and its Compounds with Answers Solutions

Carbon and its Compounds Extra Questions Very Short Answer Type

Question 1.
Draw the electron dot structure of the gas molecule which is liberated when zinc metal is treated with aqueous NaOH solution.
Answer:
Hydrogen gas,
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 1

Question 2.
Write the number of covalent bonds in the molecule of ethane.
Answer:
There are seven covalent bonds :
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 2

Question 3.
Write the number of covalent bonds in the molecule of propane, C.H.
Answer:
There are ten covalent bonds :
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 3

Question 4.
Write the number of covalent bonds in the molecule of butane, C4H10.
Answer:
There are thirteen covalent bonds :
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 4

Question 5.
Which element exhibits the property of catenation to maximum extent and why?
Answer:
Carbon exhibits the property of catenation due to strong C—C bond.

Question 6.
What is the molecular formula of the alcohol which can be derived from propane ?
Answer:
Propane : CH(b) CH3 –CH2 –CH3 Or C3 H8
Alcohol obtained from propane is C3H7OH.

Question 7.
Write the molecular formula of first two members of homologous series having functional group-Ci.
Answer:
(i) CH3Cl
(ii) C2H5Cl.

Question 8.
Write the molecular formula of first two members of homologous series having functional group -Br.
Answer:
(i) CH3Br
(ii) C2H5Br.

Question 9.
Write the molecular formula of first two members of homologous series having functional group –OH.
Answer:
(i) CH3OH
(ii) C2H5OH.

Question 10.
Give the names of thefunctional groups :
(i) –OH
(ii)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 5
Answer:
(i) Alcoholic group
(ii) Ketonic group.

Question 11.
Write the molecular formula of
(i) Methane and
(ii) Ethanol
Answer:
(i) CH4
(ii) C2H5OH.

Question 12.
Which functional groups always occur at the terminal position of a carbon chain?
Answer:
Aldehydic group R–CHO and carboxyl group R–COOH (R = alkyl group).

Question 13.
Name the functional group which always occurs in the middle of a carbon chain.
Answer:
Ketonic group always occurs in the middle of a carbon chain.

Question 14.
In an organic compound, which parts largely determine its physical and chemical properties?
Answer:
The alkyl part (carbon chain) of an organic compound detrmines its physical properties whereas the functional group detrmines its chemical properties.

Question 15.
An organic compound ‘X’ of molecular.formula C2H4O2 gives brisk effervescence with sodium bicarbonate. Give the name and formula of x.
Answer:
‘X’is ethanoic acid (an organic acid). ‘X’ → CH3COOH
CH3COOH + NaHCO3 → CH3COONa + co2 + H2O
Organic acid decomposes sodium bicarbonate and gives brisk effervescence of carbon dioxide gas.

Question 16.
Why is pure ethanoic acid called glacial ethanoic acid (or glacial acetic acid) ?
Answer:
The melting point of pure ethanoic acid is 290 K and hence it often freezes in cold climate to form a colourless, ice-like liquid. This has given it the name glacial acetic acid.

Question 17.
What is vinegar ?
Answer:
A 5-8% solution of acetic acid in water is called vinegar and is used widely as a preservative pickels.

Question 18.
How does carbon attain a stable electronic configuration ?
Answer:
Carbon attains stable electronic configuration by sharing its four electrons with other atoms.

Question 19.
What is isomerism ?
Answer:
It is phenomenon in which compounds have the same molecular formula but different structural formula.

Question 20.
Which of the following formulae represents a saturated hydrocarbon ?
CnH2n+2 CnH2n+1, CnH2n, CH2n-2
Answer:
CnH2n+2, represents a saturated hydrocarbon.

Question 21.
Which of the following are alkenes ?
CH4, C2H6, C2H4, C3H6 and C3H8.
Answer:
C2H4 and C3H6 are alkenes.

Question 22.
What happens when methane is burnt in air?
Answer:
Methane burns in air to give carbon dioxide and water.
CH4 + 2O2 → CO2 + 2H2O + Heat energy

Question 23.
(i) What happens when ethanol rects with alkaline potassium permaganate ?
Answer:
KMnO4 + C2H2OH → MnO2 + CH3CHO + KOH + H2O
(ii) Methane is mixed to chlorine gas in presence of sunlight?
Answer:
CH4 + Cl2 → CH3Cl + HCl

Question 24.
What is the next holologue of C3H7OH called ?
Answer:
The next homologue of C3H7OH is called butanol (C5H9OH).

Question 25.
Write the name and formula of the 2nd member of homologous series having general formula CnH2n
Answer:
The 2nd member is propene, C3H6.

Question 26.
Write the name and formula of 2nd member of homologous series having general formula Cn H2n+2.
Answer:
The 2nd member is ethane, C2H6.

Question 27.
Write the name and formula of the 2nd member of homologous series having general formula CnH2n-2.
Answer:
The 2nd member is propyne, C3H4.

Question 28.
Define allotropy.
Answer:
Allotropy is the property of an element to exist in different physical forms but have similar chemical properties.

Question 29.
Write the molecular formula of 2nd and the 3rd member of the homologous series whose first member is methane.
Answer:
C2H6, C3H8

Question 30.
Which two of the following organic compounds belong to the same homologous series whose first memer is methane. C2H6, C2H6O, C2H6O2, CH4O
Answer:
CH4O and C2H6O belong to the same homologous series.

Question 31.
Write the name and molecular formula of the first member of the homologous series of alkynes.
Answer:
The first member is ethyne, C2H2.

Question 32.
Write the name and molecular formula of the fourth member of alkane series.
Answer:
The fourth member of the alkane series is butane C2H10.

Question 33.
Write the structural formulae of the following compounds :
(i) Propane-2 ol
(ii) 2-hydroxy propanoic acid.
Answer:
(i)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 6
(ii)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 7

Question 34.
Name the following compounds :
(a) C3 – C2 – OH
(b)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 8
Answer:
(a) Ethanol
(b) Ethanal.

Question 35.
Select saturated hydrocarbons from the following:
C3H6; C5H10; C4H10; C6H14; C2H4
Answer:
C4H10 and C6H14 are saturated hydrocarbons.

Question 36.
Draw the structural formula of bromopentane.
Answer:
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 9

Question 37.
Write the IUPAC name of the following:
(i) CH3CH2CH2Cl
(ii)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 10
(iii) CH3COCH3
(iv)CH3 –CHOH–CH3
(vi) CH3CH2 ≡ CH
(iii) CH3CH2COCH2CH3
Answer:
(i) 1-chloropropane
(ii) 2-methyl propan-2-ol
(iii) Ethene
(iv) Propan-2-ol
(v) 1-butyne
(vi) pentan-3-one

Question 38.
The cleaning action of soaps or detergents are based on which groups ?
Answer:
A soap molecule is made up of two parts a long hydrocarbon part (non-ionic part) and a short ionic part containing – [laex]\mathrm{COONa}^{+}[/latex] group.

Question 39.
Carbon forms number of compounds due to which of its two specific proper ties?
Answer:
(i) Straight chains, Branched chains, Rings
(ii) Isomerism.

Carbon and its Compounds Extra Questions Short Answer Type

Question 1.
What is a covalent bond ? What type of bond exists in (i) CCI4, (ii) CaCl2 ?
Answer:
The chemical bonds formed between two atoms by the sharing of electrons between them is known as a covalent bond. The sharing of electrons between the two atoms takes place in such a way that both the atoms acquire stable electronic configuration of their nearest noble gas.
(i) CCl4 –Covalent bond
(ii) CaCl2 –Ionic bond.

Question 2.
Catenation is the ability of an atom to form bonds with other atoms of the same element. It is exhibited by both carbon and silicon. Compare the ability of catenation of the two elements. Give reasons.
Answer:
Carbon exhibits catenation much more than silicon or any other element due to its smaller size which makes the C—C bonds strong while the Si—Si bonds are comparatively weaker due to its large size.

Question 3.
Write down the electron dot structure (formula) of sodium chloride and magnesium oxide. Atomic Numbers: Na = 11, Mg = 12, CI = 17 and 0 = 8
Answer:
Dot structure of NaCl :
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 11

Question 4.
Write the names of the following compounds :
(a)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 12
(b)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 13
(c)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 14
(d)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 15
Answer:
(a) Pentanoic acid
(b) Butyne
(c) Heptanal
(d) Pentanol

Question 5.
Why are unsaturated hydrocarbons more reactive than saturated hydro carbons?
Answer:
Unsaturated hydrocabons are more reactive due to the presence of C = C and C = C. bond which are weaker than the single bond in saturated hydrocarbons. These double and triple bonds are the reactive sites in the unsaturated hydrocarbons wich easily give addition reactions.

Question 6.
Identify and name the functional groups present in the following compounds:
(a)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 16
(b)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 17
(c)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 18
(d)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 19
Answer:
(a) –OH Hydroxyl/Alcohol
(b)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 20
(c)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 21
(d)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 22

Question 7.
Write the name and molecular formula of an organic compound having its name suffixed with ‘-ol’ and having two carbon atoms in the molecule. With the help of a balanced equation indicate what happens when it is heated with excess of conc. H2SO4
Answer:
The organic compound is ethanol. Its molecular formula is C2H6O and structural formula is C2H5OH or CH3CH2OH.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 23

Question 8.
Complete the reaction(s) given below and classify them as Combusion/Oxidation Addition/Substitution reaction.
(i)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 24
(ii)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 25
Answer:
(i) CH3CH2COOH, Oxidation
(ii) C2H6, Addition.

Question 9.
Carbon, Group (14) element in the Periodic Table, is known to form compounds with many elements.
Write an example of a compound formed with:
(a) Chlorine (Group 17 of Periodic Table)
(b) Oxygen (Group 16 of Periodic Table).
Answer:
(a) Carbon tetrachloride (CCl4)
(b) Carbon dioxide (CO2).

Question 10.
How is ethanol obtained for commercial use ?
Answer:
When ethene is heated with concentrated sulphuric acid at 75° (348 K) and treated with water, ethanol is produced.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 26

Question 11.
Name the gas evolved when ethanoic acid reacts with sodium carbonate. How would you identify this gas?
Answer:
The gas evolved is carbon dioxide (CO2). The reaction is as follows:
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 27
When this gas is passed through lime water, it turns milky. The milky colour of lime water confirms that the gas iş carbon dioxide (CO2).

Question 12.
Write four uses of ethyl alcohol.
Answer:
(i) It is used in the manufacture of paints, medicines, dyes, soaps, etc.
(ii) It is used in the preparation of organic compounds like ether, chloroform iodoform.
(iii) It is used as a fuel in internal combusion engines.
(iv) It is used in low temperature thermometers.

Question 13.
Mention the physical properties of ethanoic acid.
Answer:
(i) It is a colourless liquid
(ii) It is sour in taste
(iii) It has a characteristics smell
(iv) It is soluble in water.

Question 14.
How will you convert ethanoic acid into methane ? Explain with the help of equations of the reactions involved.
Answer:
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 28

Question 15.
What is meant by denatured alcohol ? What is the need to denature alcohol ?
Answer:
Denatured alcohol is ethyl alcohol which has been made unfit for drinking purposes by adding poisonous substances like methanol, pyridine, copper sulphate, etc. Ethanol is an important chemical. It is supplied at concessional rates to industries. It is therefore made unfit for drinking purposes to prevent its misuse.

Question 16.
Intake of small quantity of methanol can be lethal. Comment.
Answer:
Methanol is oxidised to methal in the liver. Methanal reacts with the components of cells. It causes the protoplasm to coagulate. It also affects the optic nerve, causes blindness.

Question 17.
A gas is evolved when ethanol reacts with sodium. Name the gas evolved and also write the balanced chemical equation of the reaction involved.
Answer:
Gas evolved is hydrogen.
2CH3CH2OH + 2Na → 2CH3CH2ONa+ + H2

Question 18.
Why are detergemts better cleansing agents than soaps ?
Answer:
Detergents work as cleansing agent in hard and soft water both because the charged Water ends of detergents do not form insoluble precipitates with calcium and magnesium ions in hard water.

Question 19.
Why are soaps not suitable for washing clothes with hard water ?
Answer:
Soaps are not suitable for washing clothes with hard water because of two reasons :
(i) Soap reacts with the calcium and magnesium ions present in hard water to form insoluble precipitate called scum. This resutls in the wastage of soap.
(ii) The sticky scum sticks to the clothes being washed and interferes with the cleaning ability soap. This makes the cleaning of clothes difficult.

Question 20.
Two carbon compounds A and B have the molecular formula C3H8 and C3H6 respectively. Which one of the two is most likely to show addition reaction ? Justify your answer.
Answer:
Compound A (C3H8) is a saturated and compound B (C3H6) is an unsaturated hydrocarbon (with a double bond). As we know that addition reactions are a characteristic property of unsaturated hydrocarbons, thus the compound B (C3H6) is most likely to show addition reaction.

Question 21.
How would you bring about the following conversions ? Name the procss and write the reaction involved.
(a) Ethanol to ethene.
(b) Propanol to propanoic acid.
Answer:
(a) By the dehydration of ethanol in the presence of concentrated H2SO4.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 29
(b) By the oxidation of propanol using oxidising agent such as alkaline KMnO4.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 30

Question 22.
Ethene is formed when ethanol at 443 K is heated with excess of concentrated sulphuric acid. What is the role of sulphuric acid in this reaction ? Write the balanced chemical equation of this reaction.
Answer:
Sulphuric acid acts as a dehydrating agent.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 31

Question 23.
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: (i) Ethanol (ii) Ethanoic acid Differentiate between Ethanol and Ethanoic acids.
Answer:
An atom or a group of atoms wich determine the chemical propeties of an organic compound is called a functional group.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 32

Question 24.
What is meant by homologous séries of carbon compounds ? Classify the following carbon compounds into two homologous series and name them.
C3H4, C3H6, C4H8 C5H8, C5H10
Answer:
A group of organic compounds having the same functional group and similar structures wich the successive members differ by CH, group is called homologous series.
Alkynes : C3H4, C4H6, C5H8,
Alkenes : C3H6, C4H8, C5H10

Question 25.
What is meant by isomers ? Draw the structures of two isomers of butane, C4H10. Explain why we cannot have isomrs of first three members of alkane series.
Answer:
Isomers are compounds having the same molecualr formula but different structures. The two isomers of butane, C4H10 are :
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 33
Since branching is not possible, isomers are not possible for the first three members of alkane series.

Question 26.
Give an example each of
(i) open chain,
(ii) branched chain and
(iii) ring compounds.
Answer:
(i) Open chain compound (n-pentane)
CH3 – CH2 – CH2 – CH2 – CH3
(ii) Branched chain compound (isobutane)

Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 34
(iii) Ring (cyclopentane)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 35

Question 27.
(a) How does the supply of air affect combustion of saturated hydrocarbons ?
(b) What is indicated by :
(i) sooty flame
(ii) blue flame of a bunsen burner ?
(c) Why are holes provided at the bottom of a bunsen burner ?
Answer:
(a) If air supply is not sufficient, saturated hydrocarbons give yellow sooty flame.
(b) (i) Yellow sooty flame-Burning of unsaturated hydrocarbons such as ethene and ethyne incomplete combustion (anyone).
(ii) Blue flame-Burning of saturated hydrocarbons/complete combustion.
(c) Holes let the supply of air to be adjusted for complete combustion.

Question 28.
Explain the given reactions with examples:
(a) Combustion reaction
(b) Oxidation reaction
(c) Substitution reaction.
Answer:
(a) Combustion reaction : Carbon compounds burns in oxygen to produce carbon dioxide along with release of large amount of heat and light.
CH4 + 2O2 → CO2 + 2H2O + Heat and light
(b) Oxidation reaction : Ethanol is oxidised to ethanoic acid in the presence of alkaline KMnO4 (oxidising agent) on heating.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 36

(c) Substitution reaction : In the presence of sunlight, chlorine replaces the hydrogen atoms of hydrocarbons.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 37

Question 29.
List two tests for experimentally distinguishing between an alcohol and a carboxylic acid and describe how these tests are performed.
Answer:
(i) Test with NaHCO3 solution in water.
On adding carboxylic acid to baking soda, carbon dioxide is liberated with brisk effervescence. On adding a solution of baking soda to alcohol, no brisk effervescence occurs.

(ii) Test with blue litmus solution :
Carboxylic acid turns blue litmus red.
There is no change in colour when a blue litmus solution is added to alcohol.

Question 30.
Write physical properties of ethanol.
Answer:
Physical properties of ethanol are :

  1. Ethanol is a colourless liquid having a pleasant smell and a burning taste.
  2. Ethanol is a liquid at room temperature.
  3. Ethanol is lighter than air.
  4. Ethanol is miscible with water.
  5. Ethanol is a covalent compound.
  6. Ethanol has no effect on litmus solution.

Question 31.
Write the chemical equation of the preparation of Ethanoic acid by the oxidation of Ethanol.
Answer:
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 38

Question 32.
What is homologous series of carbon compounds ? List its any two characteristics. Write the name and formula of next higher homologous of HCOOH.
Answer:
(i) A series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called homologous series.
Characteristics of homologous series :
(a) The molecular formulae of any two successive members of a homologous series differ by CH2
(b) There is a regular gradation in physical properties of members of a homologous series.
(ii) The name of next homologous of HCOOH is ethanoic acid. Its formula is CH3COOH.

Question 33.
Two carbon compounds X and Y have the molecular formula C4H5 and C5H12 respectively. Which one of these is most likely to show addition reaction ? Justify your answer. Also give the chemical equation to explain the process of addition reaction in this case.
Answer:
C4H8 will show addition reaction because it is an unsaturated hydrocarbon due to the presence of a double bond.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 39

Question 34.
Complete the following chemical equations :
(i) CH3COOH + Na2CO3
(ii) CH4 + O2
(iii) C2H5OH + Na →
Answer:
(1 2CH3COOH + Na2CO3 → 2CH3COONa + H2O + CO2
(ii) CH4+ 2O2 → CO2 + 2H20
(iii) 2C2H5OH + 2Na → 2C2H5ONa + H2

Question 35.
A compound X is formed by the reaction of a carboxylic acid C2H4O2 and an alcohol in presence of a few drops of H2SO4. The alcohol on oxidation with alkaline KMnO4 followed by acidification gives the same carboxylic acid as used in this reaction. Give the names and structure of (a) carboxylic acid, (b) alcohol and (c) the compound X. Also write the reaction.
Answer:
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 40

Question 36.
As ester hat the molecular formula C4H8O2.Write its structural formula. What happens when this ester is heated in the presence of sodium hydroxide solution ? Write the balanced chemical equation for the reaction and name the products. What is a saponification reaction ?
Answer:
Structural formula:
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 41
When this ester is heated in the presence of sodium hydroxide solution, it changes into an alcohol and a carboxylic acid.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 42

Products : Ethanol and ethanoic acid
Saponification: Reaction of an ester with an acid or a base to give an alcohol and a carboxylic acid. This reaction is known as sapnification because it is used in the preparation of soap.

Question 37.
Name two oxidising agents that are used for the conversion of alcohols to acids. Distinguish between ethanol and ethanoic acid on the basis of (i) litmus test, and (ii) reaction with sodium hydrogen carbonate.
Answer:
The two oxidising agents are alkaline KMnO4 and acidified K2Cr2O7.
(i) Ethanol does not affect litmus paper whereas ethanoic acid turns blue litmus red.
(ii) Ethanol does not react with NaHCO3 whereas ethanoic acid gives brisk effervesence with the evolution of colourless gas, CO2.
CH3COOH + NaHCO3 → CH3COONa + H2O + CO2

Question 38.
Write the chemical reaction only:
(i) Methane reacts with chlorine in presence of Sun Light.
(ii) Ethanol is heated with excess of conc. H2SO4 at 160°C –170°C.
Answer:
(i)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 43
(ii)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 44

Question 39.
Write the structural formula of ethanol. What happens when it is heated with excess of conc. H2SO4 at 443 K ? Write the chemical equation for the reaction stating the role of conc. H2SO4 in this reaction.
Answer:
Structural formula of ethanol :
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 45
When ethanol is heated with excess of conc. H2SO4 at 443K, ethene is formed.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 46
Conc.H2SO4 acts as dehydrating agent.

Question 40.
Complete the following chemical equations :
(i) CH3COOC2H5 + NaOH →
(ii) CH3COOH + NaOH →
(iii)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 47
Answer:
(i) CH3COOC2H5 + NaOH → CH3COONa + C2H5OH
(ii) CH3COOH NaOH → CH3COONa + H2O
(iii)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 48
Question 41.
When ethanol reacts with ethanoic acid in the presence of conc. H2SO4, a substance with fruity smell is produced. Answer the following:
(i) State the class of compounds to which the fruity smellig 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) The fruity smell compounds are : esters.
Chemical equation:
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 49
Product’s chemical name: Ethyl ethanoate.
(ii) Conc. H2SO4 acts as a dehydrating agent.

Question 42.
Distinguish between esterification and saponification reactions with the help of the chemical equation for each. State one use of each (i) esters, and (ii) saponification process.
Answer:
Esterification: A process in which an alcohol and a carboxylic acid react in the presence of conc. H2SO4 to form an ester.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 50
Saponification : A process in which an ester reacts with sodium hydroxide to form sodium salt of an acid and alcohol.
CH3COOC2H5 + NaOH → CH3COONa + C2H5OH (i) Esters are used in ice creams and perfumes.
(ii) Saponification process is used in the preparation of soap.

Question 43.
What is saponification ? Write the reaction involved in this process.
Answer:
Saponification is the procss of converting esters into salts of carboxylic acids and ethanol by treating them with a base.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 51

Question 44.
Explain esterification reaction with the help of a chemical equation. Describe an activity to show esterification.
Answer:
Esterification : A process in which an alcohol and a carboxylic acid react in the presence of conc. H2SO4 to form an ester.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 52
Activity:
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 53

  1. Take 1 ml of ethanol mixed with 1 ml of acetic acid reaction along with few drops of conc. H2SO4 in a test tube.
  2. Warm it for 5 minutes in a water bath.
  3. Pour the contents in a beaker containing 20-50 mL of water and smell the resulting mixture.
  4. It will give a fruity smell indicating the formation of ester.

Question 45.
What do you mean by saturated and unsaturated hydrocarbon? Explain with example.
Answer:
Hydrocarbons: Organic compounds made up of Formation of Ester. carbon and hydrogen are called hydrocarbons.

Aliphatic Saturated Hydrocarbons: Saturated aliphatic hydrocarbons are called alkane or paraffin. All the carbon atoms in these are bonded through single bonds. The general formula of these is Cn H2n+2 and suffix “.ane” is used in their nomenclature.
e.g., CH4 (methane), C2H6 (ethane), etc.

Aliphatic Unsaturated Hydrocarbons: Those compounds in which at least one double or triple bond is present between two carbon atoms are called unsaturated hydrocarbons.
Aliphatic unsaturated hydrocarbons are of two types :
(a) Alkene: Those hydrocarbons which have at least one carbon-carbon double bond are called alkenes or olefins. The general formula of these compounds is Cn H2n, e.g., C2H4 (ethane)

(b) Alkyne: Those hydrocarbons which must have at least one carbon-carbon triple bond are called alkynes. The general common formula of these compounds is CnH2n-2.e.g., C2H2 (ethyne).

Question 46.
Write short notes on homologous series with example of alkane and alkene.
Answer:
Homologous Series: When the general formula and functional groups are same for the organic compound and these can be arranged with a molecular weight difference on 14, then a series is formed called homologous series. Each compound of the homologous series is called homolog of each other.
Hydrocarbon Series: General formula for homologous series of saturated hydrocarbons is Cn H2n+2. e.g.,
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 54
Methane, ethane, propane, butane, pentane, etc., are called homologoue of each other. General formula for homologous series of usaturated hydrocarbons, alkene is Cn H2n+2
e.g., C2H4 (ethane), C3H6 (propane)
Main Characteristics of Homologous Series

  1. All the members of a homologous series can be represented by the same general formula.
  2. Any two adjacent homologous differ by 1 carbon atom and 2 hydrogen atoms in their molecular formula.
  3. All the compounds of a homologous series show similar chemical properties.
  4. With increase in the molecular mass, a gradual change in the physical properties is seen, e.g., the melting and boiling points increase with increasing molecular mass.
  5. The difference in the molecular masses of any two adjacent homologous or members is 14 u.

Question 47.
Write structural formula of the following compounds :
Pentan-3-one
Answer:
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 55

Question 48.
Write short note on:
(i) Tetra valency of carbon
(ii) combustion
(iii) Addition Reaction
Answer:
(i) Atomic number of carbon is 6, so its electronic configuration is 2, 4. It shares its 4 valence electrons with other elements in order to complete its octet. The number of electrons shared in order to complete octet is valency, hence valency of carbon is 4.

(ii) Combustion : Organic compounds burn in oxygen and yield CO2 and water vapours. Heat and light are also released during this process. This reaction is known as combustion reaction.
e.g., C2H5OH + 3O2 → 2CO2 + 3H2O + Energy
CH4 + 2O2 → CO2 + 2H2O + Heat + light

(iii) Addition Reaction : The reaction in which a regent completely add to a reactant without the removal of small molecules are called.
Addition reacton :
Ex. Addition of hydrogen in the presence of catalysts like palladium or nickel, to unsatur ated hydrocarbons field saturated hydrocarbons.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 56

Question 49.
What is soap ? Write the chemical name and formula of any one sopa. Write any four good attributes of a soap.
Answer:
Soap : Sodium and potassium salts of long chain carboxylic acid having high atomic mass are called soaps. Soaps for cleaning are obtained by treating vegetable or animal oils and fats with a strong base such as NaOH and KOH in an aqueous solution.
This process of formation of soap is called saponification.e.g., Sodium stearate (C17H25 COONa)
Chemical Reaction for the Formation of Soap
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 57
Glycerol is obtained as a by-product in this reaction. Detergents are sythetic substances similar to soap in its property to clean dirt. The main component of detergent is sodium lauryl sulphate.
Attribute of a Good Soap :

  1. A good soap should not contain any base, as it causes damage to the clothes and skin.
  2. Soap should not break when in use.
  3. Soap should be soluble in alcohol.
  4. Soap should not contain more than 10% of water.
  5. It should contain disinfectants.

Question 50.
Write a brief note on the following:
(i) Substitution Reaction
(ii) Functional Group.
Answer:
(i) Substitution Reaction: Reaction in which atom or a group of atoms of an organic molecule is replaced or substituted by another atom or a group of atom is known as substitution reaction. e.g., Reaction of chlorine with ethylene at high temperature. Here, the hydrogen of ethylene is substituted by chlorine atom.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 58
(ii) Functional Group: Group which combine with any carbon chain and responsible for its chemical properties are called functional groups.
e.g., -OH in R-OH decide the chemical properties of this compound, thus it is a functional group.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 59

Question 51.
Explain saponification by giving chemical equations. Difference between soft and hard soaps. Write four characteristics of a good quality soap and explain its cleaning mechanism on the basis of micelle.
Answer:
When caustic soda is used as base in the chemical reaction for the formation of soap, we get hard soap, it gives less foam with water. But when we use caustic potash is used as a base we get a mild soap which gives more foam with water.
Attributes of a Good Soap :

  1. A good soap should not contain any base, as it causes damage to the clothes and skin.
  2. Soap should not break when in use.
  3. Soap should be soluble in alochol.
  4. Soap should not contain more than 10% of water.
  5. It should contain disinfectants.

Carbon and its Compounds Extra Questions Long Answer Type

Question 1.
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 detrgents instead of soaps.
Or
Soaps and detergents are both types of salts. State the difference between the two. Write the mechanism of the cleansing action of soaps. Why do soaps not form lather (foam) with hard water? Mention any two problems that arise due to the use of detergents instead of soaps.
Or
Explain the cleaning action of soap on the basis of micelle concept.
Answer:
Soaps are sodium or potassium salts of long-chain carboxylic acids. Detergents are generally ammonium or sulphonate salts of long chain carboxylic acids.
Cleaning Action of Soap
A soap molecule is mae up of two parts a long hydrocarbon part and a short ionic part containing –COONa+ group. The soap molecule is said to have a tadpole structure which can be represented as :
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 60
The long hydrocarbon chain present in soap molecule is hydrophobic so the hydrocarbon part of soap molecule is insoluble in water but soluble in oil and greae. The inic part of the soap molecule is hydrophilic, so, the ionic portion of soap molecule is soluble in water but insoluble in oil and grease. Now the dirty clothes having greasy and oily subsances.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 61

When treated with soap the greasy and only dirt particles attach themselves to the hydrocarbon part of the soap molecule. This ionic pat of the soap molecule, however, remains attached to water. When the dirty cloth is agitated in soap solution, the dirt particle the dirt particles attached to the soap molecules get washed away in water, and the cloth becomes clean. Thus, the whole purpose of using soap is to make the oily and greasy dirt particles soluble in water, so that they can be washed away with water during rinsing process.

Actually, when soap is dissolved in water, it forms a colloida suspension in which the soap molecules cluster together to form micelles (Figure (a)]. The micelles remain suspended in water because the similar negative charges at the end of each soap molecule repel each other. In a micele, the soap molecules are arranged radially, with the hydrocarbon and directed towards the centre and the ionic end directed outwards. Now, when dirty clothes are treated with this soap solution, the soap micelle entraps the dirt particlesd by attaching the hydrocarbon part of the soap molecule to the greasy or oily particles [as shown in Figure]. Since the ionic part of the soap molecules remains attached to water molecles, therefore, the greasy dirt particles get dispersed in water and the cloth becomes clean.

Soaps do not form lather in hard water because hard water contains calcium and magnesium salts. Soap moleculesd react with calcium and magnesium salts to form an insoluble precipitate called scum.
Two problems which arise because of the use of detergents are:

  • Detergents are non-biodegradable; hence, detrgents accumulate in the environment and cause problems.
  • Certain phosphate additives are added to detrgents which form a thick green scum over the river water and harm the animal life in the river.

Question 2.
What happens when :
(i) ethanol burns in air.
(ii) ethanol reacts with sodium metal.
(iii) ethanol is oxidised with chromic anhydride in glacial ethanoic acid.
(iv) ethanol is heated with alkaline potassium permanganate.
(v) ethanol is heated with ethanoic acid in the presence of a few drops of concentrated sulphuric acid ?
Or
Write equations of four chemical reactions of ethyl alcohol and also write its three uses.
Answer:
(i) Ethanol is highly inflammable liquid. It catches fire easily and starts burning. Ethanol burns readily in air with a blue flame to form carbon dioxide and water vapour :
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 62
Uses :

  1. It is used as an active ingredient in all alcohalic drinks.
  2. It is useful in medicines like tincture of iodine, cough syrup.
  3. Alcohal is used as an additive in petrol.

Question 3.
(a) What are hydrocarbons? Give examples.
(b) Give the structural differences between saturated and unsaturated hydrocarbons with two examples each.
(c) What is a functional group ? Give examples of four different functional groups.
Answer:
(a) Compounds of carbon and hydrogen are called hydrocarbons. For example, methane, ethane, etc.
(b) Saturated hydrocarbons contain carbon-carbon single bonds. Unsaturated hydrocarbons contain at least one carbon-carbon double or triple bond.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 63

(c) An atom/group of atoms joined in a specific manner which is responsible for the characteristics chemical properties of the organic compounds is called a functional group. Examples are hydroxyl group (–OH), aldehyde group (–CHO), ketonic group (C =O), carboxylic group (–COOH), etc.

Question 4.
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 ?
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:
(i) Catenation : The unique ability of carbon to form bonds with other atoms of carbon giving rise to long chains of different types of compounds.
(ii) Tetravalency: Since carbon has a balency of 4, it is capable of bonding with four other atoms of carbon or atoms of elements like oxygen, hydrogen, nitrogen, sulphur, chlorine, etc.
Carbon forms strong bonds with most other elements because of its small size which enables the nucleus to hold on to the shared pairs of electrons strongly.

Question 5.
A compound C (molecular formula, C2H4O2) reacts with Na-metal to form a compound R and evolves a gas.which burns with a pop sound. Compound Con treatment with an alcohol A in pesence of an acid forms a sweet smelling compound S (molecular formula C3 H6O2). On addition of NaOH to C, it also gives R and water. Son treatment with NaOH solution gives back R and A.
Identify C, R, A, S and write down the reaction involved.
Answer:
C – Ethanoic acid
R – Sodium salt of ethanoic acid (sodium acetate) and gas evolved is hydrogen
A – Methanol
S – Ester (Methyl acetate)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 64

Question 6.
What happens when (Write chemical equation only)
(i) methane is combusted ?
(ii) ethyl alochol reacts with acetic acid ?
(iii) ethanoic acid reacts with NaOH ?
(iv) ethanol is heated with sulphuric acid ?
Answer:
(i) CH4 + 2O2 → CO2 + 2H2O
(ii)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 65
(iii) CH3COOH + NaOH → CH3COONa + H2O
(iv)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 66

Question 7.
Write the chemical equation for the reactions of esterification of ethanoic acid and also write its reaction with NaOH and NaHCO3
Answer:
Esterification : When ethanol reacts with acetic acid in presence of an acid as catalyst, a fruity (sweet) smelling liquid called ester is obtained. This reaction is called esterifi cations.
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 67
(i) CH3COOH + NaOH → CH3COONa+ + H2O
(ii) CH3COOH + NaHCO3 → CH3COONa2+ + CO2 + H2O

Question 8.
What is glacial acetic acid ? Write chemical equations of four reactions of acetic acid.
Answer:
Ethanoic Acid : It is commonly known as acetic acid. Its formula is CH3COOH. 5-8% solution of ethanoic acid in water is known as vinegar. During winters it often freezes in cold climates and forms ice like flakes, so it is also called glacial acetic acid.
Chemical equations:
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 68

Question 9.
What happens when :(Give chemical equation only).
(i) Acetic acid reacts with sodium carbonate.
(ii) Ethanol is oxidised with alpaline solution of KMnO4
(iii) Sodium hydrogen Carbonate reacts with ethanoic acid.
(iv) Methane is combusted.
Answer:
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 69
(iii) CH3COOH + NaHCO3 → CH3COONa + CO2 + H2O
(iv)
Carbon and its Compounds Class 10 Extra Questions with Answers Science Chapter 4 70