The positive deviations from Raoult’s law mean the vapour pressure is:

1. Higher than expected.
2. Lower than expected.
3. As expected.
4. None of the above

The partial pressure of ethane over a solution containing 6.56 × 10^–2 g of ethane is 1 bar. If the solution contains 5.00 × 10^–2 g of ethane, the partial pressure of the gas will be:

1. 0.66 bar

2. 0.96 bar

3. 0.76 bar

4. 0.19 bar

At 300 K, 36 g of glucose present in a litre of its solution has an osmotic pressure of 4.98 bar. The concentration at which osmotic pressure of the solution becomes 1.52 bar at the same temperature, would be:

If the density of lake water is 1.25 g mL^–1 and contains 92 g of Na⁺ ions per kg of water, then the molality of Na⁺ ions will be:

 The correct sequence of order of increasing solubility in the n-octane is:

1. Cyclohexane < CH₃CN < CH₃OH < KCl

2. KCl < CH₃OH < CH₃CN < Cyclohexane

3. KCl < CH₃OH > CH₃CN < Cyclohexane

4. None of the above

Heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components are 105.2 kPa and 46.8 kPa respectively. The vapour pressure of a mixture of 26.0 g of heptane and 35 g of octane would be:

1. 43.45 kPa

2. 78.96 Pa

3. 73.43 kPa 

4. 65.72 Pa

An aqueous solution of 2 % (w\w) non-volatile solute exerts a pressure of 1.004 bar at the normal boiling point of the solvent. Molar mass of the solute would be:

A 5 % solution (by mass) of cane sugar in water has freezing point of 271 K. Freezing point of 5 % glucose in water would be: (freezing point of pure water is 273.15 K)

1. 279.24 K

2. –269.06 K

3. 275.42 ^oC

4. 269.06 K

Benzene and toluene form an ideal solution over the entire range of composition. The vapour pressure of pure benzene and toluene at 300 K are 50.71 mm Hg and 32.06 mm Hg respectively.

The mole fraction of benzene in vapour phase, if 80 g of benzene is mixed with 100 g of toluene, would be:

1. 0.41

2. 0.68

3. 0.72

4. 0.59

The mass of a non-volatile solute (molar mass 40 g mol^–1) that should be dissolved in 114 g octane to reduce its vapour pressure to 80 % would be:

1. 6 g

2. 7 g

3. 8 g

4. 10 g