Which of the following substances shows the highest colligative properties?

The measured osmotic pressure of a solution prepared by dissolving $17.4 \ mg$ of $K_2SO_4$ in $2 \ L$ of water at $27^{\circ} C$ is $3.735 \times 10^{-3} \ bar$. The van't Hoff factor is $(R = 0.083 \ L \ bar \ K^{-1} \ mol^{-1}$; atomic weights $K = 39, S = 32, O = 16)$.

$5 \ g$ of $Na_2SO_4$ was dissolved in $x \ g$ of $H_2O$. The change in freezing point was found to be $3.82 \ ^oC$. If $Na_2SO_4$ is $81.5 \%$ ionised,the value of $x$ ($K_f$ for water $= 1.86 \ ^oC \ kg \ mol^{-1}$) is approximately .............. $g$ (molar mass of $S = 32 \ g \ mol^{-1}$ and that of $Na = 23 \ g \ mol^{-1}$)

$17.4\%\, (w/v)$ $K_2SO_4$ $(Mw=174\, g/mol)$ solution at $27\, ^\circ C$ is isotonic to $4\%\, (w/v)\, NaOH$ solution at the same temperature. If $NaOH$ is $100\%$ ionized,what is the $\%$ ionization of $K_2SO_4$ in aqueous solution .......... $\%$.

The ratio of the value of any colligative property for $KCl$ solution to that for sugar solution is nearly

When $HgI_2$ is added to an aqueous solution of $KI$,then the: