NCERT Class 8 Science MCQ | Chapter 9: The Amazing World of Solutes, Solvents, and Solutions
1. What is a solution?
(A) A non-uniform mixture
(B) A uniform mixture of two or more substances
(C) A pure substance
(D) A mixture in which components settle at the bottom
Answer: (B) A uniform mixture of two or more substances
2. In a solution formed by dissolving salt in water, salt is called the:
(A) Solvent
(B) Solution
(C) Solute
(D) Indicator
Answer: (C) Solute
3. In a salt-water solution, water is the:
(A) Solute
(B) Solvent
(C) Compound
(D) Residue
Answer: (B) Solvent
4. When two liquids are mixed to form a solution, the substance present in the smaller amount is generally called the:
(A) Solvent
(B) Solute
(C) Residue
(D) Suspension
Answer: (B) Solute
5. Which of the following forms a non-uniform mixture with water?
(A) Sugar
(B) Salt
(C) Chalk powder
(D) Oxygen
Answer: (C) Chalk powder
6. What happens when more and more salt is added to a fixed amount of water?
(A) All the salt always dissolves
(B) A stage is reached when some salt remains undissolved
(C) The water disappears
(D) The salt changes into a gas
Answer: (B) A stage is reached when some salt remains undissolved
7. A solution in which more solute can still be dissolved at a given temperature is called:
(A) Saturated solution
(B) Unsaturated solution
(C) Concentrated solution
(D) Solid solution
Answer: (B) Unsaturated solution
8. A solution in which no more solute can dissolve at a particular temperature is called:
(A) Dilute solution
(B) Unsaturated solution
(C) Saturated solution
(D) Pure solvent
Answer: (C) Saturated solution
9. What is meant by the concentration of a solution?
(A) The amount of solvent present only
(B) The amount of solute present in a fixed quantity of solution or solvent
(C) The temperature of the solution
(D) The volume of the container
Answer: (B) The amount of solute present in a fixed quantity of solution or solvent
10. Which solution contains relatively less solute?
(A) Concentrated solution
(B) Dilute solution
(C) Saturated solution
(D) Solid solution
Answer: (B) Dilute solution
11. What is solubility?
(A) The amount of solvent present in a solution
(B) The maximum amount of solute that can dissolve in a fixed quantity of solvent at a particular temperature
(C) The volume of a solution
(D) The density of a solvent
Answer: (B) The maximum amount of solute that can dissolve in a fixed quantity of solvent at a particular temperature
12. For most solid substances, what generally happens to their solubility in water when temperature increases?
(A) It decreases
(B) It increases
(C) It becomes zero
(D) It remains exactly the same
Answer: (B) It increases
13. According to the chapter, what happens to the solubility of gases in liquids when temperature increases?
(A) It generally increases
(B) It generally decreases
(C) It always becomes zero
(D) It remains unchanged
Answer: (B) It generally decreases
14. Why is dissolved oxygen important in water?
(A) It makes water salty
(B) It supports aquatic plants, fish, and other organisms
(C) It increases the boiling point of water
(D) It changes water into a solid
Answer: (B) It supports aquatic plants, fish, and other organisms
15. Which statement about oxygen dissolved in water is correct?
(A) More oxygen generally dissolves in warm water than cold water
(B) More oxygen generally dissolves in cold water than warm water
(C) Oxygen cannot dissolve in water
(D) Oxygen dissolves only in boiling water
Answer: (B) More oxygen generally dissolves in cold water than warm water
16. What is density?
(A) Mass per unit volume
(B) Volume per unit mass
(C) Mass multiplied by volume
(D) Weight per unit temperature
Answer: (A) Mass per unit volume
17. Which formula represents density?
(A) Density = Volume ÷ Mass
(B) Density = Mass × Volume
(C) Density = Mass ÷ Volume
(D) Density = Mass + Volume
Answer: (C) Density = Mass ÷ Volume
18. What is the SI unit of density?
(A) g/mL
(B) g/cm³
(C) kg/m³
(D) kg/L
Answer: (C) kg/m³
19. An object has a mass of 27 g and a volume of 10 cm³. What is its density?
(A) 0.27 g/cm³
(B) 2.7 g/cm³
(C) 17 g/cm³
(D) 37 g/cm³
Answer: (B) 2.7 g/cm³
20. Which instrument is commonly used to measure the volume of a liquid?
(A) Digital balance
(B) Measuring cylinder
(C) Thermometer
(D) Spring balance
Answer: (B) Measuring cylinder
21. When measuring the volume of a colourless liquid in a measuring cylinder, where should the reading generally be taken?
(A) At the top of the cylinder
(B) At the bottom of the meniscus
(C) At the middle of the cylinder
(D) Above the liquid surface
Answer: (B) At the bottom of the meniscus
22. How can the volume of an irregular solid such as a stone be determined?
(A) By measuring only its length
(B) By using the water displacement method
(C) By measuring its temperature
(D) By weighing it only
Answer: (B) By using the water displacement method
23. A measuring cylinder contains 50 mL of water. After a stone is completely immersed, the level rises to 55 mL. What is the volume of the stone?
(A) 5 mL
(B) 50 mL
(C) 55 mL
(D) 105 mL
Answer: (A) 5 mL
24. What generally happens to the density of a substance when it is heated?
(A) Its density generally increases
(B) Its density generally decreases
(C) Its mass always increases
(D) Its volume always decreases
Answer: (B) Its density generally decreases
25. Why does ice float on water?
(A) Ice has a higher density than liquid water
(B) Ice has a lower density than liquid water
(C) Ice has no mass
(D) Ice dissolves in water
Answer: (B) Ice has a lower density than liquid water
NCERT Class 8 Science MCQ | Chapter 9: The Amazing World of Solutes, Solvents, and Solutions
Assertion–Reason Questions
Directions: Choose the correct option:
(A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
(B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
(C) Assertion is true, but Reason is false.
(D) Assertion is false, but Reason is true.
1. Assertion: A solution is a uniform mixture.
Reason: The solute particles are evenly distributed throughout the solvent.
Answer: (A)
2. Assertion: A saturated solution cannot dissolve more solute at a particular temperature.
Reason: It has already dissolved the maximum amount of solute possible at that temperature.
Answer: (A)
3. Assertion: The solubility of most solid substances in water increases when temperature increases.
Reason: Heating generally allows more of the solid solute to dissolve in a fixed amount of water.
Answer: (A)
4. Assertion: The solubility of gases in water generally decreases when temperature increases.
Reason: More oxygen can dissolve in cold water than in warm water.
Answer: (A)
5. Assertion: Ice floats on liquid water.
Reason: When water freezes, its structure expands and the same amount of water occupies a larger volume, making ice less dense than liquid water.
Answer: (A)
