When 20 g of naphthoic acid `(C_2H_8O_2)` is dissolved in 50 gofbenzene `(K_f "=1.72 K kg mol"^(-1)),` a freezing point depression of 2 K is observed. The van't Hoff factor (i) is

Options

A. `0.5`
B. 1
C. 2
D. 3

Answer

A

Explanation

Molality can be calculated using gien values as `m=(w_(A))/(M_(A) xx w_(B))xx 1000= (20)/(172 xx 50)xx 1000`
Therefore, `Delta T_(f)= ixx K_(f) xx m rArr 2 =I xx 1.72 xx (20)/(172 xx 50)xx 1000 rArr i=0.5`