1. When a non-volatile solute is dissolved in a pure solvent, the vapour pressure of the pure solvent
- 1) remains the same
- 2) decreases
- 3) increases
- 4) none of these
Answer: 2)
2. A liquid boils when its vapour pressure becomes equal to
- 1) very high
- 2) zero
- 3) one atmospheric pressure
- 4) very low
Answer: 3)
3. The depression in freezing point is measured by using the formula, ΔTf= Kf x m
Kf is called
- 1) molal depression constant
- 2) freezing point depression constant
- 3) cryoscopic constant
- 4) all of these
Answer: 4)
4. The ratio of the colligative effect produced by an electrolyte solution to the corresponding effect for the same concentration of a non-electrolyte solution is known as
- 1) degree of dissociation
- 2) degree of association
- 3) activity coefficient
- 4) van’t Hoff factor
Answer: 4)
5. Abnormal molecular masses are obtained when there exists
- 1) dissociation of molecules
- 2) association of molecules
- 3) either of the two
- 4) none of these
Answer: 3)
6. The freezing point of 1 molal K2SO4 solution assuming K2SO4 to be 100% ionised in water is
- 1) –1.86°C
- 2) –3.72°C
- 3) –5.58°C
- 4) +5.58°C
Answer: 3)
7. The depression in freezing point of an unknown solution is equal to the depression in freezing point of 0.1 molal aqueous solution of urea. The concentration of the unknown solution is
- 1) 0.1 M
- 2) 0.2 M
- 3) 0.5 M
- 4) 1.0 M
Answer: 1)
8. The depression in freezing point for 1 M urea, 1 M glucose and 1 M NaCl are in the ratio
- 1) 1:2:2
- 2) 1:2:1
- 3) 1:1:1
- 4) 1:1:2
Answer: 4)
9. Which one of the following is true for the van’t Hoff factor, i ?
- 1) i = ΔTf / [ΔTf]o
- 2) i = ΔTb / [ΔT b]o
- 3) i = Δp / [Δp]o
- 4) all of these
Answer: 4)
10. Which one of the following solutions would produce maximum elevation in boiling point?
- 1) 0.1 M glucose
- 2) 0.2 M sucrose
- 3) 0.1 M Ba(NO3)2
- 4) 0.1 M MgSO4
Answer: 3)
11. The highest boiling point will be observed in 1% solution of which of the following substances?
- 1) NH2–CO–NH2
- 2) C12H22O11
- 3) NaCl
- 4) Na2SO4
Answer: 4)
12. The value of van’t Hoff factor ‘i’ in case of dimerisation of benzoic acid in benzene is given by the expression
- 1) i = 1 – α
- 2) i = 1 + α
- 3) i = 1 – α/2
- 4) i = 1 + α/2
Answer: 3)
13. On dissolving common salt in water it is observed that
- 1) boiling point of the solution increases
- 2) boiling point of the solution decreases
- 3) vapour pressure is increased
- 4) freezing point is raised
Answer: 1)
14. At high altitudes, water boils at a temperature which is
- 1) higher than the normal boiling point
- 2) lower than the normal boiling point
- 3) is equal to normal boiling point
- 4) none of these
Answer: 2)
15. The ratio of the value of colligative property for K2SO4 solution to that of KCl solution at the same concentration is nearly
- 1) 1.25
- 2) 1.5
- 3) 2.0
- 4) 2.5
Answer: 2)
