Question

1 g of a non-volatile, non-electrolyte solute of molar mass
250 g/mol was dissolved in 51.2 g of benzene. If the
freezing point depression constant Kf of benzene is 5.12
kg K mol⁻¹. The freezing point of benzene is lowered by
(a) 0.3 K (b) 0.5 K
(c) 0.2 K (d) 0.4 K

Answer 1

1 g of a non-volatile, non-electrolyte solute of molar mass

250 g/mol was dissolved in 51.2 g of benzene. If the

freezing point depression constant Kf of benzene is 5.12

kg K mol⁻¹. The freezing point of benzene is lowered by 0.4 K

-formula for lowering of freezing point:

∆Tf = Kf × m

- All the data required is given in the question, so we just put all these values in the above equation

-∆Tf = (5.12 × 1 × 1000)/ 250 × 51.2

∆Tf = 0.4 K

- so the correct option is (d)