When benzoic acid dissolves in benzene,the observed molecular mass is

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 $1.86 \ K \ kg \ mol^{-1}$).

$A$ compound $MX_2$ has observed and normal molecular masses $65.6$ and $164$ respectively. Calculate the percentage of ionization of $MX_2$ ............ $\%$

When $1.5 \ g$ of phenol $(C_6H_5OH)$ is dissolved in $100 \ g$ of toluene,a decrease in freezing point of $0.56 \ K$ is observed. If the association is dimeric in nature,find the percentage of association. Given: $K_f = 4 \ K \ kg \ mol^{-1}$.

The depression in freezing point observed for a formic acid solution of concentration $0.5 \, mL \, L^{-1}$ is $0.0405^{\circ} \, C$. The density of formic acid is $1.05 \, g \, mL^{-1}$. The Van't Hoff factor of the formic acid solution is nearly: (Given for water $K_{f} = 1.86 \, K \, kg \, mol^{-1}$)

$20 \ g$ of naphthoic acid $(C_{11}H_8O_2)$ dissolved in $50 \ g$ of benzene $(K_f = 1.72 \ K \ kg \ mol^{-1})$ shows a depression in freezing point of $2 \ K$. The Van't Hoff factor is?