To $500 \mathrm{~cm}^{3}$ of water, $3.0 \times 10^{-3} \mathrm{~kg}$ of acetic acid is added. If $23 \%$ of acetic acid is dissociated, what will be the depression in freezing point? $\mathrm{K}_{\mathrm{f}}$ and density of water at $1.86 \mathrm{~K} \mathrm{~kg}-1$ and $0.0997 \mathrm{~g} \mathrm{~cm}^{-3}$
respectively.
a. $0.186 \mathrm{~K}$
b. $0.228 \mathrm{~K}$
c. $0.371 \mathrm{~K}$
d. $0.555 \mathrm{~K}$
[IIT 2000]