When of benzoic acid is dissolved in of benzene, it shows a depression in freezing point equal to …

When $2\text{ g}$ of benzoic acid is dissolved in $25\text{ g}$ of benzene, it shows a depression in freezing point equal to $1\cdot62\text{ K}$. Molal depression constant ($K_f$) of benzene is $4\cdot9\text{ K kg mol}^{-1}$ and molecular weight of benzoic acid $= 122\text{ g/mol}$. What will be the percentage association of the benzoic acid? (Benzoic acid forms dimer when dissolved in benzene.)