Physical Chemistry MCQ with Answers

Physical Chemistry MCQ with Answers

111) The vapour pressure of a liquid decreases by 10 torr when a non volatile solute is dissolved. The mole fraction of the solute in solution is 0.1. What will be the mole fraction of the liquid, if the decrease in the vapour pressure is 20 torr, the same solute being dissolved?

Answer is:

0.8

Explanation:

ΔP₁⁄ΔP₂ = mole fraction of solute 1 ⁄ mole fraction of solute 2

112) A 0.2M aqueous solution of a weak acid (HX) is 50% ionized. The freezing point of this solution is: (K_f = 1.86 kg⁄mol for water)

Answer is:

−0.56^oC

Explanation:

ΔT_f = iK_fm

113) 1.82m metal required 32.5 mL of 1N HCl to dissolve it. What is the equivalent weight for metal?

Answer is:

56

114) Calculate the amount of oxalic acid (H₂C₂O₄.2H₂O) required to obtain 250 mL of semimolar solution:

Answer is:

15.75 gm

115) The vapour pressure of a pure liquid A at 310^oC is 120 torr. The vapour pressure of this liquid in solution with liquid B is 72 torr. Calculate the mole fraction of A in solution, if the mixture obeys Raoult′s law:

Answer is:

0.6

20
21
22
23
24
25
26