A student X was doing an experiment by taking 0.15 g acetic acid in 40 g of benzene. He suddenly…

A student X was doing an experiment by taking 0.15 g acetic acid in 40 g of benzene. He suddenly observed that the freezing point of the mixture is lowered by $0.40^\circ\text{C}$. Do you think that association of acetic acid has taken place? If yes, what will be degree of association ($K_f$ of benzene = $5.12\text{ K kg mol}^{-1}$)?