11) Which among the following is true?

i. When vapour pressure of the liquid increases its boiling point decreases.
ii. When vapour pressure of the liquid increases its boiling point increases.
iii. When vapour pressure of the liquid decreases its boiling point decreases.
iv. When vapour pressure of the liquid decreases its boiling point increases.

a) i & iii.
b) i & iv.
c) ii & iii.
d) ii & iv.

ANSWER : i & iv.

12) Vapour pressure decreases with:

a) increase in concentration of the solution.
b) decrease in solute particles in the solution.
c) decrease in boiling point.
d) increase in freezing point.

ANSWER : increase in concentration of the solution.

13) Positive deviation from Raoult’s law is observed when:

a) inter molecular forces of attraction between the two liquids is greater than that between individual liquids.
b) inter molecular forces of attraction between the two liquids is smaller than that between individual liquids.
c) force of attraction between two liquids is greater than that between individual liquids.
d) force of attraction between two liquids is smaller than that between individual liquid.

ANSWER : force of attraction between two liquids is smaller than that between individual liquid.

14) If a solute is in associated state then Vant Hoff factor is:

a) i = 1
b) i > 1
c) i = 0
d) i < 1

ANSWER : i < 1

15) Which of the following statements are correct:

i. colligative property depends upon number of solute of particles present in the solution.
ii. Relative lowering of vapour pressure of a solution is equal to the mole fraction of the non-volatile non-electrolyte solute.

a) i
b) ii
c) Both i & ii
d) None of the above

ANSWER : Both i & ii

16) Addition of common salt in water causes

a) increase in M.P of solution.
b) increase in B.P of solution.
c) decrease in B.P of solution.
d) decrease in both M.P & B.P.

ANSWER : increase in B.P of solution.

17) The value of Vant Hoff factor (i) = 2 is for:

a) glucose
b) sucrose
c) calcium chloride
d) sodium chloride.

ANSWER : sodium chloride.

18) Addition of non-volatile solute in water results in:

a) an increase in melting point of the liquid.
b) a decrease in the boiling point of the liquid.
c) a decrease in the vapour pressure of the liquid.
d) no change in the boiling point of the liquid.

ANSWER : a decrease in the vapour pressure of the liquid.

19) The osmotic pressure of a solution of cane sugar is 5.07 atm at 150°C ( molecular mass = 342). What is the percent of the solution of cane sugar?

a) 5%
b) 6%
c) 6.75%
d) 5.75%

ANSWER : 5%

20) What is the vapour pressure of pure liquid A at 27°C if it forms an ideal solution with another liquid B, the vapour pressure and mole fraction of pure liquid B at 27°C is 140 torr and 0.2 respectively. The total vapour pressure of the solution is 84 torr at 27°C.

a) 56 torr.
b) 140 torr.
c) 70 torr.
d) 17 torr.

ANSWER : 70 torr. 

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