The vapour pressure of a solvent decreases by 10 mm of mercury when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be if the decrease in vapour pressure is to be 20 mm of mercury then the mole fraction of the solvent is [CBSE PMT 1998]

(1) 0.8

(2) 0.6

(3) 0.4

(4) None

Osmotic pressure is 0.0821 atm at a temperature of 300 K. Find concentration in mole/litre [Roorkee 1990]

(1) 0.033

(2) 0.066

(3) 0.33 × 10^–2

(4) 3

The osmotic pressure of 5 % (mass-volume) solution of cane sugar at 150 °C (mol. mass of sugar = 342 g/mole) is:

A solution containing 3.3 g of a substance in 125 g of benzene (b.p. 80°C) boils at 80.66°C. If K_b for one litre of benzene is 3.28°C, the molecular weight of the substance shall be 

1. 127.20

2. 131.20

3. 137.12

4. 142.72

The molal b.p. constant for water is $0{.513}^{o}Ckgmo{l}^{-1}$. When 0.1 mole of sugar is dissolved in 200 g of water, the solution boils under a pressure of 1 atm at

(1) 100.513°C

(2) 100.0513°C

(3) 100.256°C

(4) 101.025°C

An aqueous solution containing 1 g of urea boils at 100.25 °C. The aqueous solution containing 3 g of glucose in the same volume will boil at:
1. 100.75 °C
2. 100.5 °C
3. 100 °C
4. 100.25 °C

Solution of sucrose (Mol. Mass = 342) is prepared by dissolving 34.2 gm of it in 1000 gm of water. Freezing point of the solution is (K_f for water is 1.86 K kg mol^–1) [AIEEE 2003]

(1) 272.814 K

(2) 278.1 K

(3) 273.15 K

(4) 270 K

An aqueous solution of a weak monobasic acid containing 0.1 g in 21.7 g of water freezes at 272.817K. If the value of K_f for water is 1.86 K kg mol^–1, the molecular mass of the acid is [AMU 2002]

(1) 46.0

(2) 48.6

(3) 48.8

(4) 46.8

What is the molality of the solution of a certain solute in a solvent if there is a freezing point depression of 0.184° and if the freezing point constant is 18.4 K kg mol⁻¹

1. 0.01

2. 1.00

3. 0.001

4. 100

A solution containing 6.8 g of a non-ionic solute in 100 g of water was found to freeze at −0.93 ^oC. The freezing point depression constant of water is 1.86. The molecular weight of the solute is-