The Van't Hoff factor will be highest for

Van't Hoff factor of $Hg_{2}Cl_{2}$ in its aqueous solution will be : ($Hg_{2}Cl_{2}$ is $80\%$ ionized in the solution) :- (in $.6$)

Which of the following has the same van't Hoff factor $(i)$ as $K_3[Fe(CN)_6]$?

The freezing point of a solution prepared by adding $8.1 \ g$ of $HBr$ ($90\%$ ionized) to $100 \ g$ of water is $...... \ ^\circ C$. (Given $K_f$ for water $= 1.86 \ K \ kg \ mol^{-1}$)

Which of the following solutions in water possesses the lowest vapour pressure?

The freezing point depression constant for water is $1.86 \, ^\circ C \, m^{-1}$. If $5.00 \, g$ of $Na_2SO_4$ is dissolved in $45.0 \, g$ of $H_2O$,the freezing point is changed by $3.82 \, ^\circ C$. Calculate the van't Hoff factor $(i)$ for $Na_2SO_4$.