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Class 8 Science Chapter 9 The Amazing World of Solutes Solvents and Solutions MCQ
The Amazing World of Solutes Solvents and Solutions MCQ
Class 8 Science Chapter 9 MCQ Online Test
Question 1.
Which of the following best defines a solution?
(a) A pure substance made of one kind of particle
(b) A solid mixed with air
(c) A uniform mixture of solute and solvent
(d) A liquid that changes shape
Answer:
(c) A uniform mixture of solute and solvent
Question 2.
A solution has the following features
I. It is a uniform mixture.
II. It contains a solute and a solvent.
III. It is always solid in nature.
Choose the correct option
(a) Both I and II
(b) Both I and III
(c) Both II and III
(d) I, II and III
Answer:
(a) Both I and II
Question 3.
What do we call the liquid component in which a solute dissolves?
(a) Concentrate
(b) Soluble
(c) Solvent
(d) Diffuser
Answer:
(c) Solvent
Question 4.
When a solute completely dissolves in a solvent, the result is called a
(a) compound
(b) soluble gas
(c) solution
(d) saturate
Answer:
(c) solution
Question 5.
While performing an activity, Aditi kept adding salt to water and noticed that after a few spoons, the salt no longer dissolved and settled at the bottom. What does this indicate? (Competency Based Que.)
(a) Salt has turned into stone
(b) Water has reached its solubility limit
(c) Salt cannot dissolve in water at all
(d) The salt is expired
Answer:
(b) Water has reached its solubility limit
Question 6.
A solution that contains more solute than the solvent can dissolve at a given temperature is called
(a) unsaturated solution
(b) dilute solution
(c) saturated solution
(d) concentrated solution
Answer:
(c) saturated solution
Question 7.
Which of the following represents an unsaturated solution?
(a) Salt remains undissolved
(b) No more solute can dissolve
(c) All solute dissolves completely
(d) Solute forms a separate layer
Answer:
(c) All solute dissolves completely
Question 8.
Which term describes a solution that has less solute compared to another solution of the same solvent?
(a) Saturated
(b) Concentrated
(c) Dilute
(d) Soluble
Answer:
(c) Dilute
Question 9.
What does the term ‘concentration of a solution’ refer to?
(a) The colour of the solution.
(b) The temperature of the solution.
(c) The amount of solute present in a fixed amount of solution (or solvent).
(d) The pressure applied to the solution.
Answer:
(c) The amount of solute present in a fixed amount of solution (or solvent).
Question 10.
Which of the following terms is used to describe the maximum amount of solute that can dissolve in a solvent at a given temperature?
(a) Solubility
(b) Concentration
(c) Density
(d) Saturation
Answer:
(a) Solubility
Question 11.
Read the statements given below about the nature of solutions and solubility.
(i) A solute is the substance that gets dissolved in a solvent.
(ii) The solubility of a solute increases with temperature in most cases.
(iii) A saturated solution can dissolve more solute at the same temperature.
(iv) Water is a commonly used solvent in everyday life. Choose the combination of statements which are true:
(a) (i), (ii), (iv)
(b) (ii), (iii), (iv)
(c) (i), (iii), (iv)
(d) (i), (ii), (iii)
Answer:
(a) (i), (ii), (iv)
Question 12.
In an experiment, Priya observed that when the water temperature was raised from 30 °C to 70 °C, more baking soda dissolved. What does this show? (Competency Based Que.)
(a) Temperature decreases solubility.
(b) Solubility increases with temperature.
(c) Baking soda becomes solid at high temperature.
(d) Water becomes thicker.
Answer:
(b) Solubility increases with temperature.
Question 13.
Why does the same substance dissolve more in water when the water is heated?
(a) Heat changes the solute
(b) Heating increases solubility
(c) Heating makes water lighter
(d) Heating decreases concentration
Answer:
(b) Heating increases solubility
Question 14.
Which of the following shows the correct order of increasing solubility in water (at room temperature)?
(a) Chalk powder < salt < lemon juice
(b) Salt < lemon juice < chalk powder
(c) Lemon juice < chalk powder < salt
(d) Chalk powder < lemon juice < salt
Answer:
(d) Chalk powder < lemon juice < salt
Question 15.
The smallest volume that can be read from a 100 mL measuring cylinder is
(a) 10 mL
(b) 2 mL
(c) 1 mL
(d) 0.1 mL
Answer:
(c) 1 mL
Question 16.
Rishabh used a measuring cylinder and looked from above to read the water level. His reading was incorrect. What should he have done? (Competency Based Que.)
(a) Tilted the cylinder slightly
(b) Read from the side at any level
(c) Read at eye level from the bottom of the meniscus
(d) Used a beaker instead
Answer:
(c) Read at eye level from the bottom of the meniscus
Question 17.
Why is it important to observe the bottom of the meniscus when reading a measuring cylinder?
(a) It gives an accurate reading
(b) It shows the solute level
(c) It tells the mass
(d) It marks the air level
Answer:
(a) It gives an accurate reading
Question 18.
Tanvi measured the volume of a cuboidal box using length, width and height. She then calculated the volume as 1000 cm3. What formula did she use? (Competency Based Que.)
(a) Volume = l + w +h
(b) Volume = l × w × h
(c) Volume = l – w – h
(d) Volume = l ÷ w ÷ h
Answer:
(b) Volume = l × w × h
Question 19.
The rise in water level when an object is added to a measuring cylinder is used to find
(a) mass of the object
(b) solubility of the object
(c) volume of the object
(d) density of water
Answer:
(c) volume of the object
Question 20.
Which of the following statements best explains why the Earth’s inner layers are denser than the outer ones?
(a) The inner layers contain heavier metals.
(b) Pressure and temperature increase as we go deeper and making materials heavier and more compact.
(c) The outer layers lose mass over time.
(d) Light gases rise from the Earth’s core.
Answer:
(b) Pressure and temperature increase as we go deeper and making materials heavier and more compact.
Question 21.
The diagram below shows a hot air balloon rising. Based on the concept of density, which of the following is the correct explanation? (Competency Based Que.)
(a) The balloon is lighter due to the decrease in air pressure inside.
(b) Hot air is less dense and moves upward.
(c) The balloon pushes heavier gases down to rise.
(d) The mass of air inside the balloon becomes zero.
Answer:
(b) Hot air is less dense and moves upward.
Question 22.
Why does ice float om water, even though both are made of the same substance?
(a) Ice has more particles than water.
(b) Ice has lower mass than the same volume of water.
(c) Ice particles move faster and rise.
(d) Ice is heavier than water.
Answer:
(b) Ice has lower mass than the same volume of water.
Question 23.
Which of the following mixtures is an example of an uniform solution formed by a solid dissolving in a liquid?
(a) Chalk powder in water
(b) Oil in water
(c) Sugar in water
(d) Sand in water
Answer:
(c) Sugar in water
Question 24.
Why is it not possible to dissolve more solute in a saturated solution at the same temperature?
(a) The solvent becomes too light.
(b) The solute reacts with the solvent.
(c) All spaces between solvent particles are already occupied.
(d) The solution evaporates too quickly.
Answer:
(c) All spaces between solvent particles are already occupied.
Question 25.
Why is water often referred to as the ‘universal solvent’ in the study of solutions?
(a) It dissolves only gases.
(b) It can dissolve a large number of substances.
(c) It is used in laboratories.
(d) It is present in oceans and rivers.
Answer:
(b) It can dissolve a large number of substances.
Question 26.
Select a statement that will best describe the case of what happens when salt is added to water and stirred?
(a) Salt evaporates
(b) Salt floats on water
(c) Salt remains visible at the bottom
(d) Salt disperses to form a uniform mixture
Answer:
(d) Salt disperses to form a uniform mixture
Question 27.
Identify which of the following mixtures will show separation due to difference in densities of the components?
(a) Salt dissolved in water
(b) Oil floating over water
(c) Sugar completely mixed in water
(d) Ink mixed in water
Answer:
(b) Oil floating over water
The Amazing World of Solutes Solvents and Solutions Class 8 Assertion Reason Questions
The following questions consist of two statements.
Assertion (A) and Reason (R). Answer the following questions by selecting the appropriate option given below
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Question 1.
Assertion (A) A uniform mixture has the same appearance and composition throughout.
Reason (R) The solute particles are evenly spread among the solvent particles in a solution.
Answer:
(a) Both A and R are true and R is the correct explanation of A. In a uniform mixture or solution, particles mix so well that the mixture looks the same throughout, and this happens due to even distribution of solute.
Question 2.
Assertion (A) Water is called the universal solvent.
Reason (R) Water can dissolve every known substance in the world.
Answer:
(c) A is true, but R is false. Water is called a universal solvent because it dissolves many substances but not all. Some substances like oil do not dissolve in water.
Question 3.
Assertion (A) Concentrated solutions have more solute dissolved in a fixed amount of solvent.
Reason (R) Increasing the amount of solvent in a concentrated solution makes it more saturated.
Answer:
(c) A is true, but R is false. A concentrated solution have more solute, but adding more solvent makes it more dilute, not saturated. Saturation depends on the maximum solubility at a given temperature.
Question 4.
Assertion (A) A saturated solution cannot dissolve more solute at the same temperature.
Reason (R) The solute occupies all the interparticle spaces in the solvent.
Answer:
(b) Both A and R are true, but R is not the correct explanation of A. In a saturated solution, the solvent cannot dissolve more solute because it has reached its maximum capacity at that temperature, not because of interparticle spaces alone.
Question 5.
Assertion (A) Measuring cylinders are commonly used to measure the volume of liquids in science labs.
Reason (R) Measuring cylinders provide accurate readings of mass of solids.
Answer:
(d) A is true, but R is false. Measuring cylinders are used to measure volume of liquids, not the mass of solids.
Question 6.
Assertion (A) Stirring a solution helps in speeding up the process of dissolving the solute in the solvent.
Reason (R) When a solution is stirred, the solute particles are evenly distributed and come in contact with more solvent particles.
Answer:
(a) Both A and R are true and R is the correct explanation of A.
Question 7.
Assertion (A) Salt and sugar can dissolve in water to form a solution.
Reason (R) Solutes always settle down in water.
Answer:
(c) A is true, but R is false.
The Amazing World of Solutes Solvents and Solutions Class 8 Case Based MCQ Questions
Question 1.
Ravi visited an aquarium and saw different types of fish swimming actively in large water tanks. He noticed small air pumps constantly bubbling air into the tanks. He wondered why the aquarium needed those pumps. Later, the guide explained that these pumps help maintain a proper oxygen level for the fish. On another visit, he saw a pond where fish were floating lifelessly. A signboard nearby mentioned that the water temperature had risen unusually during the Summer. (Competency Based Que.)
(i) What allows fish and other aquatic animals to breathe underwater?
(a) Water produces oxygen.
(b) Gases form inside fish.
(c) Oxygen is dissolved in water.
(d) Fish do not need oxygen.
Answer:
(c) Oxygen is dissolved in water.
(ii) What happens to the solubility of oxygen in water when water is heated?
(a) It increases
(b) It remains unchanged
(c) It first increases then decreases
(d) It decreases
Answer:
(d) It decreases
(iii) Which of the following is a correct reason for aquatic animals struggling in hot water bodies?
(a) Lack of food in hot water.
(b) Water becomes toxic when heated.
(c) Dissolved oxygen is reduced in hot water.
(d) Fish do not like warm temperatures.
Answer:
(c) Dissolved oxygen is reduced in hot water.
Question 2.
Meena was preparing lemonade. She mixed sugar, lemon juice, and water, then stirred the mixture thoroughly. Her brother asked her how the sugar disappeared. She replied that it had become part of the drink and could not be seen anymore. (Competency Based Que.)
(i) Which component in the lemonade mixture acts as the solute?
(a) Lemon juice
(b) Sugar
(c) Water
(d) The glass
Answer:
(b) Sugar
(ii) Identify the correct combination for a solution
(a) solid + solid → solution
(b) liquid + gas → solution
(c) solute + solvent → solution
(d) solvent + container → solution
Answer:
(c) solute + solvent → solution
(iii) Which statement best explains the term “solution”?
(a) A solid settles at the bottom of the liquid.
(b) Two substances remain separate after mixing.
(c) A clear mixture where solute is uniformly spread in solvent.
(d) A solid floats in the liquid without dissolving.
Answer:
(c) A clear mixture where solute is uniformly spread in solvent.
The Amazing World of Solutes Solvents and Solutions Class 8 Fill in the blanks
1. When a solute mixes completely with a solvent to form a uniform mixture, the resulting substance is called a _____________ .
Answer:
solution
2. A solid solute like salt dissolves faster in water when the water is stirred or its _____________ is increased.
Answer:
temperature
3. A solution in which the amount of solute is less compared to the solvent is called a _____________ solution.
Answer:
dilute
4. In a saturated solution, the solute stops dissolving and starts _____________ at the bottom of the container.
Answer:
settling
5. The ability of a substance to dissolve in a given solvent is called its _____________ .
Answer:
solubility
6. The density of a substance is defined as the ratio of its _____________ to its volume, and it helps determine whether an object will float or sink in a given liquid.
Answer:
mass
7. The substance that gets dissolved in a solution is known as the _____________ .
Answer:
solute
8. A solution that contains the maximum amount of solute at a given temperature is called a _____________ solution.
Answer:
saturated
9. The solute particles occupy the _____________ between the particles of the solvent during dissolution.
Answer:
spaces
10. A solution that can still dissolve more solute is called an _____________ solution.
Answer:
unsaturated
The Amazing World of Solutes Solvents and Solutions Class 8 True or False
1. All substances dissolve completely in every solvent.
Answer:
False. Different substances dissolve in different solvents depending on their solubility and the nature of the solute and solvent.
2. A solution is a uniform mixture of solute and solvent.
Answer:
True.
3. The component present in a smaller amount in a solution is called the solvent.
Answer:
False. The component present in smaller amount is called the solute, while the one in larger amount is the solvent.
4. Solubility of most solids increases with increase in temperature.
Answer:
True.
5. Stirring has no effect on how fast a solute dissolves in a solvent.
Answer:
False. Stirring increases the rate of dissolution by helping solute particles mix faster with the solvent.
6. A solution is a type of mixture in which all components are evenly distributed and forming a single phase.
Answer:
True
7. Lemonade is a uniform mixture where sugar, salt and lemon juice are dissolved in water.
Answer:
True
8. A saturated solution can still dissolve more solute if we stir it for longer.
Answer:
False
The Amazing World of Solutes Solvents and Solutions Class 8 Match the following
Question 1.
Match the Column I with Column II.
| Column I | Column II |
| A. Solute | 1. Mass per unit volume of a substance |
| B. Solvent | 2. Present in smaller quantity in solution |
| C. Water | 3. Uniform mixture of solute and solvent |
| D. Solution | 4. Present in larger quantity in solution |
| E. Density | 5. Known as the universal solvent |
Answer:
A – 2, B – 4, C – 5, D – 3, E – 1
| Column I | Column II |
| A. Solute | 2. Present in smaller quantity in solution |
| B. Solvent | 4. Present in larger quantity in solution |
| C. Water | 5. Known as the universal solvent |
| D. Solution | 3. Uniform mixture of solute and solvent |
| E. Density | 1. Mass per unit volume of a substance |
Question 2.
Match the Column I with Column II.
| Column I | Column II |
| A. Saturated solution | 1. Contains small amount of solute |
| B. Unsaturated solution | 2. Cannot dissolve more solute at given temperature |
| C. Solubility | 3. More solute can still dissolve |
| D. Temperature | 4. Maximum solute that dissolves in a solvent |
| E. Dilute | 5. Affects solubility solids |
Answer:
A – 2, B – 3, C – 4, D – 5, E – 1
| Column I | Column II |
| A. Saturated solution | 2. Cannot dissolve more solute at given temperature |
| B. Unsaturated solution | 3. More solute can still dissolve |
| C. Solubility | 4. Maximum solute that dissolves in a solvent |
| D. Temperature | 5. Affects solubility solids |
| E. Dilute | 1. Contains small amount of solute |
Question 3.
Match the Column I with Column II.
| Column I | Column II |
| A. Solute | 1. Liquid in which solute dissolves |
| B. Solvent | 2. Salt in salt water |
| C. Solution | 3. Uniform mixture of solute and solvent |
| D. Saturated solution | 4. Cannot dissolve more solute at same temperature |
| E. Unsaturated solution | 5. Can dissolve more solute |
Answer:
A – 2, B – 1, C – 3, D – 4, E – 5
| Column I | Column II |
| A. Solute | 2. Salt in salt water |
| B. Solvent | 1. Liquid in which solute dissolves |
| C. Solution | 3. Uniform mixture of solute and solvent |
| D. Saturated solution | 4. Cannot dissolve more solute at same temperature |
| E. Unsaturated solution | 5. Can dissolve more solute |