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Solutions WBJEE MCQ & Practice Questions

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Solutions Revision Guide for WBJEE Chemistry

Solutions deals with concentration terms, vapour pressure and colligative properties. Many exam questions are short numericals where correct units and interpretation are more important than lengthy calculation.

For WBJEE Chemistry, revise mole fraction, molarity, molality, Raoult law, ideal and non-ideal behaviour, elevation of boiling point, depression of freezing point and osmotic pressure.

Important Topics

  • Concentration terms
  • Raoult law
  • Ideal and non-ideal solutions
  • Colligative properties
  • van’t Hoff factor
  • Osmotic pressure

Important Formulae & Relationships

  • Molarity M = moles of solute / volume of solution (L)
  • Molality m = moles of solute / mass of solvent (kg)
  • ΔTb = iKb m
  • ΔTf = iKf m
  • π = iCRT

Use formulas only after checking the required units, sign convention and assumptions for the question.

What to practise in Solutions

Concept Revision

Revise definitions, principles, equations, trends and core ideas from Solutions before attempting MCQs.

Exam-style MCQs

Use chapter-focused multiple-choice practice to improve accuracy, recall and application for WBJEE Chemistry.

Performance Practice

Attempt ChemNexa tests, review results and return to weak areas for another round of targeted revision.

Top 20 Solutions MCQs with Answers

These public questions are selected from the exact Solutions chapter, screened for topic relevance and deduplicated so repeated versions of the same MCQ are not shown publicly. Use them for quick revision, then sign in to attempt the complete test experience with more questions, results and performance review.

WBJEE Chemistry · Solutions · Very Very Hard

1. Solution concept check: Adding a nonvolatile solute to a solvent generally causes its vapour pressure to:

  • A. Decrease
  • B. Increase
  • C. Remain unchanged
  • D. Become atmospheric
Answer: A
Explanation: The solvent mole fraction falls and Raoult's law predicts lower vapour pressure.

WBJEE Chemistry · Solutions · Very Very Hard

2. Negative deviation from Raoult's law occurs when A-B interactions are:

  • A. Absent
  • B. Always zero
  • C. Stronger than A-A and B-B interactions
  • D. Weaker than like interactions
Answer: C
Explanation: Stronger unlike attractions reduce escaping tendency and vapour pressure.

WBJEE Chemistry · Solutions · Very Very Hard

3. Adding a nonvolatile solute to a solvent generally causes its vapour pressure to:

  • A. Remain unchanged
  • B. Become atmospheric
  • C. Decrease
  • D. Increase
Answer: C
Explanation: The solvent mole fraction falls and Raoult's law predicts lower vapour pressure.

WBJEE Chemistry · Solutions · Very Very Hard

4. Solution concept check: Raoult's law for a volatile component i is:

  • A. p_i=x_i/P
  • B. p_i=x_i RT
  • C. p_i=x_i p_i°
  • D. p_i=p_i°/x_i
Answer: C
Explanation: Partial vapour pressure equals liquid-phase mole fraction times pure-component vapour pressure.

WBJEE Chemistry · Solutions · Very Very Hard

5. Solution concept check: Negative deviation from Raoult's law occurs when A-B interactions are:

  • A. Stronger than A-A and B-B interactions
  • B. Weaker than like interactions
  • C. Absent
  • D. Always zero
Answer: A
Explanation: Stronger unlike attractions reduce escaping tendency and vapour pressure.

WBJEE Chemistry · Solutions · Very Very Hard

6. WBJEE advanced: Negative deviation from Raoult's law occurs when A-B interactions are:

  • A. Absent
  • B. Always zero
  • C. Stronger than A-A and B-B interactions
  • D. Weaker than like interactions
Answer: C
Explanation: Stronger unlike attractions reduce escaping tendency and vapour pressure.

WBJEE Chemistry · Solutions · Very Very Hard

7. Raoult's law for a volatile component i is:

  • A. p_i=x_i p_i°
  • B. p_i=p_i°/x_i
  • C. p_i=x_i/P
  • D. p_i=x_i RT
Answer: A
Explanation: Partial vapour pressure equals liquid-phase mole fraction times pure-component vapour pressure.

WBJEE Chemistry · Solutions · Very Very Hard

8. For an ideal binary solution of volatile liquids, total vapour pressure is:

  • A. p_A°p_B°
  • B. x_A+x_B
  • C. p_A°/x_A
  • D. x_A p_A° + x_B p_B°
Answer: D
Explanation: Dalton's law combined with Raoult's law gives the total pressure.

WBJEE Chemistry · Solutions · Very Very Hard

9. An ideal solution approximately obeys Raoult's law:

  • A. Only at boiling point
  • B. Never
  • C. Over the entire composition range
  • D. Only at infinite dilution
Answer: C
Explanation: Ideal solutions follow Raoult's law throughout composition.

WBJEE Chemistry · Solutions · Very Very Hard

10. Positive deviation from Raoult's law occurs when A-B interactions are:

  • A. Stronger than A-A and B-B
  • B. Exactly identical always
  • C. Ionic only
  • D. Weaker than A-A and B-B interactions
Answer: D
Explanation: Weaker unlike interactions allow molecules to escape more readily.

WBJEE Chemistry · Solutions · Very Very Hard

11. A solution showing positive deviation from Raoult's law often has ΔH_mix:

  • A. Undefined
  • B. Positive
  • C. Negative
  • D. Zero necessarily
Answer: B
Explanation: Energy is commonly absorbed when unlike interactions are weaker.

WBJEE Chemistry · Solutions · Very Very Hard

12. A solution showing negative deviation from Raoult's law often has ΔH_mix:

  • A. Negative
  • B. Positive
  • C. Zero necessarily
  • D. Infinite
Answer: A
Explanation: Formation of stronger unlike interactions commonly releases heat.

WBJEE Chemistry · Solutions · Very Very Hard

13. Relative lowering of vapour pressure for a dilute solution of nonvolatile solute equals approximately:

  • A. Mole fraction of solute
  • B. Mole fraction of solvent
  • C. Molality squared
  • D. Molarity of solvent
Answer: A
Explanation: Raoult's law gives (p°-p)/p°=x_solute.

WBJEE Chemistry · Solutions · Very Very Hard

14. Elevation in boiling point is represented by:

  • A. ΔT_b=K_f m
  • B. ΔT_b=RT
  • C. ΔT_b=m/K_b
  • D. ΔT_b=K_b m
Answer: D
Explanation: For a dilute nonelectrolyte solution, boiling elevation is proportional to molality.

WBJEE Chemistry · Solutions · Very Very Hard

15. Consider: (I) molality is temperature independent; (II) positive Raoult deviation can give minimum-boiling azeotrope; (III) π=CRT for dilute nonelectrolyte solution; (IV) complete CaCl2 dissociation ideally gives i=3. Which are correct?

  • A. I, III and IV only
  • B. I, II, III and IV
  • C. I and II only
  • D. II and III only
Answer: B
Explanation: All four statements are correct.

WBJEE Chemistry · Solutions · Very Very Hard

16. Solution concept check: For an ideal binary solution of volatile liquids, total vapour pressure is:

  • A. p_A°/x_A
  • B. x_A p_A° + x_B p_B°
  • C. p_A°p_B°
  • D. x_A+x_B
Answer: B
Explanation: Dalton's law combined with Raoult's law gives the total pressure.

WBJEE Chemistry · Solutions · Very Very Hard

17. Solution concept check: An ideal solution approximately obeys Raoult's law:

  • A. Over the entire composition range
  • B. Only at infinite dilution
  • C. Only at boiling point
  • D. Never
Answer: A
Explanation: Ideal solutions follow Raoult's law throughout composition.

WBJEE Chemistry · Solutions · Very Very Hard

18. Solution concept check: Positive deviation from Raoult's law occurs when A-B interactions are:

  • A. Ionic only
  • B. Weaker than A-A and B-B interactions
  • C. Stronger than A-A and B-B
  • D. Exactly identical always
Answer: B
Explanation: Weaker unlike interactions allow molecules to escape more readily.

WBJEE Chemistry · Solutions · Very Very Hard

19. Solution concept check: A solution showing positive deviation from Raoult's law often has ΔH_mix:

  • A. Negative
  • B. Zero necessarily
  • C. Undefined
  • D. Positive
Answer: D
Explanation: Energy is commonly absorbed when unlike interactions are weaker.

WBJEE Chemistry · Solutions · Very Very Hard

20. Solution concept check: A solution showing negative deviation from Raoult's law often has ΔH_mix:

  • A. Zero necessarily
  • B. Infinite
  • C. Negative
  • D. Positive
Answer: C
Explanation: Formation of stronger unlike interactions commonly releases heat.

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Solutions Practice Tests

Solutions Frequently Asked Questions

Which concentration unit is temperature independent?

Molality is based on mass of solvent and therefore does not change with temperature, unlike molarity which depends on solution volume.

Why is the van’t Hoff factor used?

It accounts for association or dissociation of solute particles so that observed colligative properties can be related to the effective number of dissolved particles.

How can I improve accuracy in Solutions numericals?

Convert masses, volumes and molecular masses carefully, write the chosen concentration unit explicitly and check whether association or dissociation affects the particle count.

Continue with another chapter to build connected concepts and strengthen your overall Chemistry preparation.

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