Which of the following solutes has the ratio of theoretical molar mass to the experimentally observed molar mass equal to $3$?

Consider the dissociation of the weak acid $HX$ as given below:
$HX_{(aq)} \rightleftharpoons H^{+}_{(aq)} + X^{-}_{(aq)}, K_{a} = 1.2 \times 10^{-5}$
$[K_{a}: \text{ dissociation constant}]$
The osmotic pressure of $0.03 \ M$ aqueous solution of $HX$ at $300 \ K$ is ............... $\times 10^{-2} \ bar$ (nearest integer).
$[\text{Given: } R = 0.083 \ L \ bar \ mol^{-1} \ K^{-1}]$

Write the value of the van't Hoff factor $(i)$ for $K_{2}SO_{4}$ and $K_{4}[Fe(CN)_{6}]$.

In which of the following solutions are ions present?

At higher altitude,the boiling point of water is $95\,^oC$. The amount of $NaCl$ added to $1\,kg$ of water $(K_b = 0.52\,K\,kg\,mol^{-1})$ in order to raise the boiling point of the solution to $100\,^oC$ (assume $90\%$ ionisation of $NaCl$) is .......... $g$.

Which solution has the maximum boiling point?