Liquid Solution

Benzoic acid undergoes dimerization in benzene. xg of benzoic acid (molar mass 122gmol−1 ) is dissolved in 49g of benzene. The depression in freezing point is 1.12K. If degree of association of acid is 88%, what is the value of x ? (Kf. for benzene =4.9‌Kkg‌mol−1)