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When 20 g of naphthoic acid (C(11)H(8)O(...

When `20 g` of naphthoic acid `(C_(11)H_(8)O_(2))` is dissolved in `50 g` of benzene `(K_(f)=1.72 K kg mol^(-1))`, a freezing point depression of `2 K` is observed. The Van't Hoff factor (i) is

A

0.5

B

1

C

2

D

3

Text Solution

Verified by Experts

The correct Answer is:
A
Actual molecular weight of naphthoic acid `(C_(11)H_8O_2)=172`
Molecular mass (calculated) `=(1000 K_fxx w)/(Wxx DeltaT_f)=(1000xx1.72xx20)/(50xx2)=344`
Van’ t Hoff factor (i) `=("Actual mol. Mass")/("Calculated mol. Mass") =(172)/(344)=0.5`
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