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

$A$ solute undergoes association in a solution to form a dimer. Which of the following values of the van't Hoff factor $i$ is possible?

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 [$K_f = 1.72 \ K \ kg \ mol^{-1}$].

$20 \ g$ of a binary electrolyte (molar mass = $100 \ g \ mol^{-1}$) is dissolved in $500 \ g$ of water. The freezing point of the solution is $-0.74 \ ^oC$. Given $K_f = 1.86 \ K \ kg \ mol^{-1}$,the degree of dissociation of the electrolyte is ......... $\%$.

The Van't Hoff factor of $BaCl_2$ at a concentration of $0.01 \ M$ is $1.98$. The percentage dissociation of $BaCl_2$ at this concentration will be: (in $\%$)

The molecular weight of $NaCl$ determined by osmotic pressure method will be