Acetic acid dissolved in benzene shows a molecular mass of

Assertion : Molecular mass of benzoic acid when determined by colligative properties is found high.
Reason : Dimerisation of benzoic acid.

Three particles of a solute $A$ associate in benzene to form a trimer $A_3$. Calculate the freezing point of a $0.25 \ m$ solution if the degree of association of solute $A$ is $0.80$. The freezing point of benzene is $5.5 \ ^oC$ and $K_f$ is $5.12 \ K \ kg \ mol^{-1}$. (Answer in $K$)

When $20 \ g$ of naphthoic acid $(C_{11}H_8O_2)$ is dissolved in $50 \ g$ of benzene, a freezing point depression of $2 \ K$ is observed. The van't Hoff factor $(i)$ is [$K_f = 1.72 \ K \ kg \ mol^{-1}$].

When $2.44 \ g$ of benzoic acid $(C_6H_5COOH)$ is dissolved in $25 \ g$ of benzene, it shows a depression of freezing point equal to $2.2 \ K$. The molal depression constant of benzene is $5.0 \ K \ kg \ mol^{-1}$. What is the percentage association of the acid, if it forms a dimer in the solution (in $\%$)?

The values of observed and calculated molecular weight of silver nitrate are $90$ and $170$ respectively. The degree of dissociation of silver nitrate is ......... $\%$.