Solutions · Question 13

'W' g of a non-volatile electrolyte solid solute of molar mass 'M' g mol-1 when dissolved in 100 mL water, decreases vapour pressure of water from 640 mm Hg to 600 mm Hg. If aqueous solution of the electrolyte boils at 375 K and Kb for water is 0.52 K kg mol-1, then the mole fraction of the electrolyte solute (x2) in the solution can be expressed as (Given : density of water = 1 g/mL and boiling point of water = 373 K)

1. 162.6 WM
2. 1.38 MW
3. 2.616 MW
4. 1.38 WM

At 298 K, the mole percentage of N2(g) in air is 80\%. Water is in equilibrium with air at a pressure of 10 atm. What is the mole fraction of N2(g) in water at 298 K? (KH for N2 is 6.5 107 mmHg)

1. 9.35 10-5
2. 9.35 105
3. 1.23 10-7
4. 1.17 10-4

Two liquids A and B form an ideal solution at temperature T K. At T K, the vapour pressures of pure A and B are 55 and 15 kN m-2 respectively. What is the mole fraction of A in solution of A and B in equilibrium with a vapour in which the mole fraction of A is 0.8?

1. 0.5217
2. 0.480
3. 0.340
4. 0.663

Which one of the following graphs accurately represents the plot of partial pressure of CS2 vs its mole fraction in a mixture of acetone and CS2 at constant temperature?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

Two liquids A and B form an ideal solution. At 320 K, the vapour pressure of the solution, containing 3 mol of A and 1 mol of B is 500 mm Hg. At the same temperature, if 1 mol of A is further added to this solution, vapour pressure of the solution increases by 20 mm Hg. Vapour pressure (in mm Hg) of B in pure state is . (Nearest integer)

Consider a solution of CO2(g) dissolved in water in a closed container. Which one of the following plots correctly represents variation of log (partial pressure of CO2 in vapour phase above water) [y-axis] with log (mole fraction of CO2 in water) [x-axis] at 25 ?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below

1. Both Statement I and Statement II are true
2. Statement I is true but Statement II is false
3. Statement I is false but Statement II is true
4. Both Statement I and Statement II are false

Elements P and Q form two types of non-volatile, non-ionizable compounds PQ and PQ2. When 1 g of PQ is dissolved in 50 g of solvent 'A', Tb was 1.176 K while when 1 g of PQ2 is dissolved in 50 g of solvent 'A', Tb was 0.689 K. (Kb of 'A' = 5 K kg mol-1). The molar masses of elements P and Q (in g mol-1) respectively, are :

1. 25, 60
2. 60, 25
3. 65, 145
4. 70, 110

The osmotic pressure of a living cell is 12 atm at 300 K. The strength of sodium chloride solution that is isotonic with the living cell at this temperature is g L-1. (Nearest integer) Given : R = 0.08 L atm K-1 mol-1 Assume complete dissociation of NaCl (Given: Molar mass of Na and Cl are 23 and 35.5 g mol-1 respectively.)

A substance 'X' (1.5 g) dissolved in 150 g of a solvent 'Y' (molar mass = 300 g mol-1) led to an elevation of the boiling point by 0.5 K. The relative lowering in the vapour pressure of the solvent 'Y' is 10-2. (nearest integer) [Given: Kb of the solvent = 5.0 K kg mol-1] Assume the solution to be dilute and no association or dissociation of X takes place in solution.