Determination of the molar mass of acetic acid in benzene using freezing point depression is affected by

The molecular mass of acetic acid $(CH_3COOH)$ dissolved in water is $60$,whereas when dissolved in benzene,it is $120$. This difference in behavior is because:

If $0.15 \ m$ aqueous solution of $KCl$ freezes at $-0.51^{\circ} C$,calculate the van't Hoff factor of $KCl$ (cryoscopic constant of water is $1.86 \ K \ kg \ mol^{-1}$).

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

If a solution prepared by adding $6.1 \ g$ of benzoic acid $(C_6H_5COOH)$ in $500 \ g$ of benzene freezes at $-0.290 \ ^oC$,find the percentage of association. (Given: $K_f$ of benzene $= 5.12 \ K \ kg/mol$,freezing point of pure benzene $= 5.50 \ ^oC$,molar mass of benzoic acid $= 122 \ g/mol$) (in $\%$)

If the degree of association is $70 \%$ for the reaction $2 A \rightleftharpoons (A)_2$,the van't-Hoff factor for the solute $A$ is