If 8 g of a non-electrolyte solute is dissolved in 114 g of n-octane to reduce its vapor pressure to 80 %, the molar mass (in g mol^–1) of the solute is -

[Molar mass of n-octane is 114 g mol^–1]

1.	40	2.	60
3.	80	4.	20

Isotonic solutions have the same:

1. Vapour pressure

2. Freezing temperature

3. Osmotic pressure

4. Boiling temperature

Vapour pressure of chloroform $\left(CHC{l}_3\right)$ and dichloromethane $\left(C{H}_{2}C{l}_2\right)$ at $25°C$ are 200 mmHg and 41.5 mmHg respectively. Vapour pressure of the solution was obtained by mixing 25.5 g of $\left(CHC{l}_3\right)$ and 40 g of $\left(C{H}_{2}C{l}_2\right)$ at the same temperature will be: (Molecular mass of $\left(CHC{l}_3\right)$ = 119.5 u and molecular mass of $\left(C{H}_{2}C{l}_2\right)$ = 85 u)

A 0.1 molal aqueous solution of a weak acid (HA) is 30 % ionized. If K_f for water is 1.86 °C/m, the freezing point of the solution will be:

200 mL of an aqueous solution contains 1.26 g of protein. The osmotic pressure of this solution at 300 K is found to be 2.57 × 10^–3 bar. The molar mass of protein will be:

(R = 0.083 L bar mol^–1 K^–1):

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

1. 68 torr

2. 140 torr

3. 72 torr

4. 20 torr

A solution of urea (molar mass 56 g mol^–1) boils at 100.18 ºC at atmospheric pressure. If K_f and K_b for water are 1.86 and 0.512 K kg mol^–1 respectively, the above solution will freeze at:

1. –6.54 ºC

2. –0.654 ºC

3. 6.54 ºC

4. 0.654 ºC

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

The addition of water vapour does not change the density of:

1. CCl₄

2. CS₂

3. Ether

4. Coke

1 % (w/w) solution of a compound is isotonic with 5 % (w/w) sucrose (sugar) solution. The molecular weight of the compound will be: