In a solution with molality $m$,if the solute exists in the form of a dimer,which of the following cannot be the elevation in the boiling point of the solution?

Solute $A$ associates in water. When $0.7 \ g$ of solute $A$ is dissolved in $42.0 \ g$ of water,it depresses the freezing point by $0.2^{\circ} C$. The percentage association of solute $A$ in water is $..... \ \%$.
[Given: Molar mass of $A = 93 \ g \ mol^{-1}$. Molal depression constant of water is $1.86 \ K \ kg \ mol^{-1}$]

When acetic acid is dissolved in benzene,its molecular mass:

$20 \ g$ 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 freezing point of a $0.262 \ mol \ kg^{-1}$ solution of acetic acid in benzene is $277.4 \ K$. If the $K_f$ value for benzene is $5.0 \ K \ kg \ mol^{-1}$ and the freezing point of pure benzene is $278.4 \ K$,then the van't Hoff factor is ...........

$75.2 \ g$ of phenol is added to $1 \ kg$ of solvent. The depression in freezing point is $7 \ K$. If phenol undergoes dimerization,calculate the percentage of association. $(K_f = 14 \ K \ kg \ mol^{-1})$