MCQs on Solutions – Class 12 Chemistry (NCERT)

Physical Chemistry – MCQ Titles (NCERT Based)
Course: CBSE Class 12 Chemistry – MCQs with Answers and Explanations

The following 50 Multiple Choice Questions (MCQs) are strictly based on the NCERT Class 12 Chemistry chapter “Solutions”. They are organized section-wise to cover conceptual, numerical, and application-based questions, making them ideal for CBSE board exam preparation.

Section A: Basic Concepts of Solutions

1. A solution is defined as:

A. A heterogeneous mixture
B. A pure substance
C. A homogeneous mixture
D. A colloidal system

Correct Answer: C
Explanation: A solution is a homogeneous mixture of two or more substances with uniform composition throughout.

2. The component present in smaller amount in a solution is called:

A. Solvent
B. Solute
C. Dispersed phase
D. Medium

Correct Answer: B
Explanation: Solute is the substance that gets dissolved in the solvent.

3. Which of the following is a solid solution?

A. Air
B. Sugar in water
C. Brass
D. CO₂ in water

Correct Answer: C
Explanation: Brass is a solid solution of copper and zinc.

4. The concentration of a solution depends on:

A. Nature of solute
B. Temperature
C. Amount of solute and solvent
D. Pressure only

Correct Answer: C
Explanation: Concentration depends on relative amounts of solute and solvent.

5. Which of the following is a volatile solute?

A. NaCl
B. Glucose
C. Ethanol
D. Sugar

Correct Answer: C
Explanation: Ethanol is volatile and can vaporize easily.

Section B: Concentration Terms

6. Molarity is defined as:

A. Moles of solute per kg of solvent
B. Moles of solute per litre of solution
C. Grams of solute per litre
D. Percentage by mass

Correct Answer: B
Explanation: Molarity (M) = moles of solute / volume of solution in litres.

7. Unit of molality is:

A. mol L⁻¹
B. g L⁻¹
C. mol kg⁻¹
D. kg mol⁻¹

Correct Answer: C
Explanation: Molality is moles of solute per kg of solvent.

8. Which concentration term is temperature independent?

A. Molarity
B. Molality
C. Normality
D. Formality

Correct Answer: B
Explanation: Molality depends on mass, not volume, hence independent of temperature.

9. Mole fraction of a component lies between:

A. 0 and 1
B. 0 and 100
C. –1 and +1
D. 1 and 10

Correct Answer: A
Explanation: Mole fraction is a ratio and has no unit, always between 0 and 1.

10. Percentage by mass is calculated as:

A. Mass of solute / mass of solvent × 100
B. Mass of solute / mass of solution × 100
C. Volume of solute / volume of solution × 100
D. Moles of solute / moles of solution × 100

Correct Answer: B
Explanation: It is defined as mass of solute divided by mass of solution.

Section C: Solubility of Solids in Liquids

11. Solubility of a solid generally:

A. Decreases with temperature
B. Increases with temperature
C. Remains constant
D. Becomes zero

Correct Answer: B
Explanation: Most solids dissolve better at higher temperatures.

12. Maximum amount of solute that dissolves at a given temperature is called:

A. Concentration
B. Molarity
C. Solubility
D. Saturation

Correct Answer: C
Explanation: Solubility is the maximum amount of solute dissolved in a solvent.

13. Which factor does not affect solubility of a solid?

A. Temperature
B. Nature of solute
C. Nature of solvent
D. Pressure

Correct Answer: D
Explanation: Pressure has negligible effect on solid solubility.

14. Sugar dissolves in water because:

A. Sugar is ionic
B. Sugar is nonpolar
C. Strong solute–solvent interactions exist
D. Sugar dissociates completely

Correct Answer: C
Explanation: Hydrogen bonding between sugar and water favors dissolution.

15. A saturated solution contains:

A. No solute
B. Maximum solute at a given temperature
C. Less solute than required
D. Excess solvent

Correct Answer: B
Explanation: Saturated solution holds maximum solute at a specific temperature.

Section D: Solubility of Gases in Liquids

16. Solubility of gases in liquids increases with:

A. Increase in temperature
B. Decrease in pressure
C. Increase in pressure
D. Increase in volume

Correct Answer: C
Explanation: According to Henry’s law, solubility ∝ pressure.

17. Henry’s law is applicable to:

A. Solids in liquids
B. Liquids in liquids
C. Gases in liquids
D. Gases in gases

Correct Answer: C
Explanation: Henry’s law relates gas solubility with pressure.

18. Soft drinks are bottled under high pressure to:

A. Reduce volume
B. Increase solubility of CO₂
C. Increase sweetness
D. Reduce temperature

Correct Answer: B
Explanation: Higher pressure dissolves more CO₂ in liquid.

19. Solubility of gases decreases with increase in:

A. Pressure
B. Temperature
C. Density
D. Volume

Correct Answer: B
Explanation: Gas molecules escape more easily at higher temperatures.

20. Bends in divers occur due to:

A. Nitrogen bubbles in blood
B. Oxygen toxicity
C. Carbon dioxide release
D. Low pressure oxygen

Correct Answer: A
Explanation: Rapid decrease in pressure causes nitrogen to form bubbles.

Section E: Vapour Pressure of Liquid Solutions

21. Vapour pressure of a solution containing non-volatile solute is:

A. Equal to solvent
B. Greater than solvent
C. Less than solvent
D. Zero

Correct Answer: C
Explanation: Non-volatile solute lowers vapour pressure of solvent.

22. Raoult’s law applies to:

A. Ideal solutions
B. Electrolytes
C. Colloids
D. Suspensions

Correct Answer: A
Explanation: Raoult’s law is valid for ideal solutions.

23. An ideal solution shows:

A. ΔHmix ≠ 0
B. ΔVmix ≠ 0
C. No deviation from Raoult’s law
D. Association

Correct Answer: C
Explanation: Ideal solutions obey Raoult’s law over entire range.

24. Vapour pressure lowering depends on:

A. Nature of solute
B. Nature of solvent
C. Number of solute particles
D. Temperature only

Correct Answer: C
Explanation: It is a colligative property.

25. Which solution shows positive deviation from Raoult’s law?

A. Acetone + chloroform
B. Benzene + toluene
C. Ethanol + acetone
D. Water + sugar

Correct Answer: C
Explanation: Weaker interactions cause higher vapour pressure.

Section F: Colligative Properties

26. Colligative properties depend on:

A. Nature of solute
B. Nature of solvent
C. Number of solute particles
D. Chemical nature

Correct Answer: C
Explanation: They depend only on number of particles.

27. Which is not a colligative property?

A. Osmotic pressure
B. Elevation in boiling point
C. Depression in freezing point
D. Surface tension

Correct Answer: D
Explanation: Surface tension depends on nature of liquid.

28. Osmotic pressure is maximum for:

A. Dilute solution
B. Concentrated solution
C. Pure solvent
D. Saturated solution

Correct Answer: B
Explanation: Higher concentration gives higher osmotic pressure.

29. Reverse osmosis is used for:

A. Milk processing
B. Desalination of water
C. Sugar purification
D. Air separation

Correct Answer: B
Explanation: Reverse osmosis removes dissolved salts from water.

30. Elevation in boiling point occurs because:

A. Vapour pressure increases
B. Vapour pressure decreases
C. Density decreases
D. Solvent evaporates

Correct Answer: B
Explanation: Lower vapour pressure requires higher temperature to boil.

Section G: Abnormal Molar Mass and van’t Hoff Factor

31. van’t Hoff factor (i) accounts for:

A. Volume change
B. Density change
C. Association or dissociation
D. Temperature variation

Correct Answer: C
Explanation: It corrects abnormal colligative property values.

32. For dissociation, van’t Hoff factor is:

A. Less than 1
B. Equal to 1
C. Greater than 1
D. Zero

Correct Answer: C
Explanation: Dissociation increases number of particles.

33. For association, van’t Hoff factor is:

A. Greater than 1
B. Less than 1
C. Equal to 1
D. Infinite

Correct Answer: B
Explanation: Association reduces number of particles.

34. Which electrolyte shows highest van’t Hoff factor?

A. NaCl
B. K₂SO₄
C. AlCl₃
D. Glucose

Correct Answer: C
Explanation: AlCl₃ dissociates into four ions.

35. Abnormal molar mass is observed due to:

A. Temperature change
B. Pressure change
C. Association/dissociation
D. Density change

Correct Answer: C
Explanation: Particle number affects colligative properties.

Section H: Exam-Oriented Mixed MCQs

36. Freezing point depression is directly proportional to:

A. Molarity
B. Molality
C. Mole fraction
D. Density

Correct Answer: B
Explanation: ΔTf = Kf × molality.

37. Which solution has highest boiling point?

A. 0.1 m glucose
B. 0.1 m NaCl
C. 0.1 m AlCl₃
D. Pure water

Correct Answer: C
Explanation: AlCl₃ produces maximum particles.

38. Ideal solution shows:

A. Endothermic mixing
B. Exothermic mixing
C. No heat change on mixing
D. Gas evolution

Correct Answer: C
Explanation: ΔHmix = 0 for ideal solutions.

39. Which colligative property is used to determine molar mass of polymers?

A. Vapour pressure lowering
B. Osmotic pressure
C. Boiling point elevation
D. Freezing point depression

Correct Answer: B
Explanation: Osmotic pressure is measurable even for large molar masses.

40. Which is a non-electrolyte?

A. NaCl
B. KNO₃
C. Glucose
D. HCl

Correct Answer: C
Explanation: Glucose does not ionize in solution.

41. Mole fraction of solvent in a solution is:

A. Always 1
B. Less than 1
C. Greater than 1
D. Zero

Correct Answer: B
Explanation: Some fraction is occupied by solute.

42. Which solution obeys Raoult’s law most closely?

A. Benzene + toluene
B. Ethanol + water
C. Acetone + chloroform
D. HCl + water

Correct Answer: A
Explanation: Similar molecular nature forms ideal solution.

43. Cryoscopic constant relates to:

A. Boiling point
B. Freezing point
C. Vapour pressure
D. Osmotic pressure

Correct Answer: B
Explanation: It is used in freezing point depression.

44. Ebullioscopic constant is used for:

A. Freezing point depression
B. Boiling point elevation
C. Osmotic pressure
D. Vapour pressure lowering

Correct Answer: B
Explanation: It relates elevation in boiling point to molality.

45. Which statement is correct?

A. Colligative properties depend on solute nature
B. Vapour pressure is a colligative property
C. Osmotic pressure is colligative
D. Density is colligative

Correct Answer: C
Explanation: Osmotic pressure depends on number of particles.

46. Osmosis occurs when:

A. Two solutions are separated by glass
B. Two solutions separated by semipermeable membrane
C. Solvent evaporates
D. Solute diffuses

Correct Answer: B
Explanation: Semipermeable membrane allows solvent flow.

47. Which is a colligative property?

A. Surface tension
B. Viscosity
C. Osmotic pressure
D. Density

Correct Answer: C
Explanation: Depends only on particle number.

48. Molality is preferred over molarity because:

A. Easier to calculate
B. Temperature independent
C. Volume independent
D. Less accurate

Correct Answer: B
Explanation: Mass does not change with temperature.

49. Which factor affects vapour pressure of a solution?

A. Color
B. Odour
C. Temperature
D. Shape of container

Correct Answer: C
Explanation: Vapour pressure increases with temperature.

50. Solutions chapter mainly deals with:

A. Chemical reactions
B. Physical properties of mixtures
C. Nuclear chemistry
D. Electrolysis

Correct Answer: B
Explanation: Solutions focus on physical behavior of homogeneous mixtures.

✅ End of NCERT-Based MCQs on Solutions – Class 12 Chemistry