The molar volume of liquid benzene (density= 0.877 g ml^-1) increases by a factor of 2750 as it vapourises at 20$°\mathrm{C}$. At 27$°\mathrm{C}$ when a non-volatile solute (that does not dissociate) is dissolved in 54.6cm3 of benzene, vapour pressure of this solution, is found to be 98.88 mm Hg. calculate the freezing point of the solution.

Given: Enthalpy of vapourisation of benzene(l)=394.57 Jg^-1. Enthalpy of fusion of benzene (l) = 10.06 kJ mol^-1 Molal depression constant for benzene=5.0 K kg mol^-1.

1. 177.65 K

2. 277.65 K

3. 517.65 K

4. 237.15 K

The depression in the freezing point of water when 10 g of CH₃CH₂CHClCOOH is added to 250 g of water is -K_a=1.4 X 10^-3, K_f=1.86K kg mol^-1

1. 0.15$°\mathrm{C}$

2. 2.15$°\mathrm{C}$

3. 1.15$°\mathrm{C}$

4. 0.65$°\mathrm{C}$

Which of the following 0.1 M aqueous solutions will have the lowest freezing point?

A solution of 18 g of glucose in 1000 g of water is cooled to -0.2 ^oC. The amount of ice separating out from this solution is -

[K_f(H₂O) = 1.86 K molal^-1]

1000 gm of 1 m sucrose solution in water is cooled to -3.534$°\mathrm{C}$. What weight of ice would be separated out at this temperature ? ${\mathrm{K}}_{\mathrm{f}}^{\text{'}}\left({\mathrm{H}}_2\mathrm{O}\right)=1.86 \mathrm{K} {\mathrm{mol}}^{-1}\mathrm{kg}.$

1. 352.98 gm.

2. 252.98 gm.

3. 302.98 gm.

4. 152.12 gm