Solutions · Question 42

1.00 g of a 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 K kg mol-1, the freezing point of benzene will be lowered by

1. 0.2 K
2. 0.4 K
3. 0.3 K
4. 0.5 K

A solution containing 10 g per dm3 of urea (molecular mass = 60 g mol-1) is isotonic with a 5% solution of a nonvolatile solute. The molecular mass of this nonvolatile solute is

1. 200 g mol-1
2. 250 g mol-1
3. 300 g mol-1
4. 350 g mol-1

The mole fraction of the solute in one molal aqueous solution is

1. 0.009
2. 0.018
3. 0.027
4. 0.036

The vapour pressure of two liquids P and Q are 80 and 60 torr, respectively. The total vapour pressure of solution obtained by mixing 3 mole of P and 2 mole of Q would be

1. 72 torr
2. 140 torr
3. 68 torr
4. 20 torr

A solution has a 1 : 4 mole ratio of pentane to hexane. The vapour pressures of the pure hydrocarbons at 20 are 440 mm Hg for pentane and 120 mm Hg for hexane. The mole fraction of pentane in the vapour phase would be

1. 0.200
2. 0.549
3. 0.786
4. 0.478

A solution of urea (mol. mass 60 g mol-1) boils at 100.18 at the atmospheric pressure. If Kf and Kb for water are 1.86 and 0.512 K kg mol-1 respectively, the above solution will freeze at

1. 0.654
2. -0.654
3. 6.54
4. -6.54

Formation of solution from two components can be considered as (i) Pure solvent separated solvent molecules, H1 (ii) Pure solute separated solute molecules, H2 (iii) Separated solvent and solute molecules solution, H3 Solution so formed will be ideal if

1. Hsoln = H1 + H2 + H3
2. Hsoln = H1 + H2 - H3
3. Hsoln = H1 - H2 - H3
4. Hsoln = H3 - H1 - H2

A solution containing components A and B follows Raoult's law when

1. A-B attraction force is greater than A-A and B-B
2. A-B attraction force is less than A-A and B-B
3. A-B attraction force remains same as A-A and B-B
4. volume of solution is different from sum of volumes of solute and solvent

A solution contains non-volatile solute of molecular mass M2. Which of the following can be used to calculate the molecular mass of solute in terms of osmotic pressure?

1. M2 = ( m2 )VRT
2. M2 = ( m2V ) RT
3. M2 = ( m2V ) RT
4. M2 = ( m2V ) RT

Pure water can be obtained from sea water by

1. centrifugation
2. plasmolysis
3. reverse osmosis
4. sedimentation