Which of the following will have the highest boiling point at $1 \ atm$ pressure?

The boiling point (in ${}^{\circ}C$) of $0.1 \, molal$ aqueous solution of $CuSO_{4} \cdot 5H_{2}O$ at $1 \, bar$ is closest to $.....$
[Given : Ebullioscopic (molal boiling point elevation) constant of water,$K_{b}=0.512 \, K \, kg \, mol^{-1}$ ]

The degree of dissociation of a $0.2 \, m$ aqueous solution of a weak acid $HX$ is $0.3$. If $K_f$ for water is $1.85 \, K \, kg \, mol^{-1}$,then the freezing point of the solution will be approximately ........... $^oC$.

Which of the following solutes dissolved in water,having the same concentration,exhibits the highest value of colligative property?

For a $0.25 \ m$ solution of $SrCl_2$,the van't Hoff factor is found to be $2.5$. What will be the effective molality of the solution in $m$?

Which of the following pairs has the same freezing point?