The equal weight of a solute is dissolved in an equal weight of two solvents A and B to form a very dilute solution. The relative lowering of vapour pressure for solution B has twice the relative lowering of vapour pressure for solution A.
If and are the molecular weights of solvents A and B respectively, then:
1. =
2. = 2
3. = 4
4. = 2
If the molality of the dilute solution is doubled, the value of molal depression constant (Kf) will be-
1. Halved
2. Tripled
3. Unchanged
4. Doubled
Consider the following statements about the composition of the vapour over an ideal 1:1 molar mixture of benzene and toluene. The correct statement is:
Assume that the temperature is constant at 25 oC.
(Given, vapour pressure data at 25 °C, benzene = 12.8 kPa, toluene = 3.85 kPa)
1. | The vapour will contain a higher percentage of toluene. |
2. | The vapour will contain equal amounts of benzene and toluene. |
3. | Not enough information is given to make a prediction. |
4. | The vapour will contain a higher percentage of benzene. |
An aqueous solution is 1.00 molal in KI. The vapour pressure of the solution can be increased by:
1. Addition of NaCl
2. Addition of Na2SO4
3. Addition of 1.00 molal Kl
4. Addition of water
A solution containing 10 g/dm3 of urea (molecular mass = 60 g mol-1) is isotonic with a 5 % solution of a non-volatile solute. The molecular mass of this non-volatile solute is:
1. | 25 g mol-1 | 2. | 300 g mol-1 |
3. | 350 g mol-1 | 4. | 200 g mol-1 |
1.00 g of non-electrolyte solute (molar mass 250 g mol-1) was dissolved in 51.2 g of benzene. If the freezing point depression constant, Kf of benzene is 5.12 mol-1 kg K, the freezing point of benzene will be lowered by:
1. 0.4 K
2. 0.3 K
3. 0.5 K
4. 0.2 K
The mixture among the following that forms maximum boiling azeotrope is:
1. | Heptane + Octane | 2. | Water + Nitric acid |
3. | Ethanol + Water | 4. | Acetone + Carbon disulphide |
Freezing point of an aqueous solution is -0.166C. Elevation of boiling point of same solution would be-
(Kb = 0.512 K m-1 and Kf = 1.66 K m-1)
1. | 0.18°C | 2. | 0.05°C |
3. | 0.09°C | 4. | 0.23°C |