The addition of a polar solvent to a solid electrolyte results in

$A$ sample of water is found to contain $5.85 \% \left(\frac{w}{w}\right)$ of $AB$ (molecular mass $58.5$) and $9.50 \% \left(\frac{w}{w}\right)$ $XY_2$ (molecular mass $95$). Assuming $80 \%$ ionisation of $AB$ and $60 \%$ ionisation of $XY_2$, the freezing point of the water sample is: [Given, $K_f$ for water $= 1.86 \ K \ kg \ mol^{-1}$, freezing point of pure water $= 273 \ K$ and $A, B, X, Y$ are monovalent ions.] (in $K$)

Which of the following aqueous solutions should have the highest boiling point?

An aqueous solution is prepared by dissolving $0.1 \ mol$ of an ionic salt in $1.8 \ kg$ of water at $35^{\circ} C$. The salt remains $90 \%$ dissociated in the solution. The vapour pressure of the solution is $59.724 \ mm \ Hg$. Vapor pressure of water at $35^{\circ} C$ is $60.000 \ mm \ Hg$. The number of ions present per formula unit of the ionic salt is . . . . . .

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 Van't Hoff factor will be highest for