Which of the following has the highest boiling point?

Which of the following $0.1 \ m$ aqueous solutions exhibits the highest osmotic pressure at $25^{\circ}C$?

If $BaCl_2$ ionizes to an extent of $80 \%$ in aqueous solution, the value of van't Hoff factor is

$A$ 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 $K$)

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

For a $0.01 \ m$ aqueous solution of $K_4[Fe(CN)_6]$,if $K_b = 0.52 \ K \ kg \ mol^{-1}$ for the solvent,then its boiling point will be ..... $^\circ C$.