Question

Elevation in boiling point for 1.5 molal solution of glucose in water is 4 K. The depression in freezing point for 4.5 molal solution of glucose in water is 4 K. The ratio of molal elevation constant to molal depression constant (Kb/Kf) is ___.

Answer 1

The correct answer is 3
ΔTb = i × Kb × m
ΔTf = i × Kf × m i = 1
4 = 1 × Kb × 1.5
4 = 1 × Kf × 4.5
$\frac{K_b}{K_f} = 3$