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

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

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

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

1. 0.06 M

2. 0.12 M

3. 0.08 M

4. 0.36 M

 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

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-

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

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 -

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

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