Which of the following aqueous solutions has the highest freezing point?

$0.6 \, mL$ of acetic acid $(CH_{3}COOH)$,having density $1.06 \, g \, mL^{-1}$,is dissolved in $1 \, L$ of water. The depression in freezing point observed for this strength of acid was $0.0205^{\circ} \, C$. Calculate the van't Hoff factor and the dissociation constant of acid.

$pH$ of a $0.1 \ M$ monobasic acid is found to be $2$. Hence its osmotic pressure at a given temperature $T \ K$ is (in $RT$)

Which of the following $0.05 \ M$ aqueous solution will have the lowest freezing point?

$A$ solution containing $10 \ g$ of an electrolyte $AB_2$ in $100 \ g$ of water boils at $100.52^{\circ} C$. The degree of ionization of the electrolyte $(\alpha)$ is............ $\times 10^{-1}$.
(nearest integer)
[Given : Molar mass of $AB_2 = 200 \ g \ mol^{-1}$,$K_{b}$ (molal boiling point elevation constant of water) $= 0.52 \ K \ kg \ mol^{-1}$,boiling point of water $= 100^{\circ} C$;
$AB_2$ ionises as $AB_2 \rightarrow A^{2+} + 2B^{-}$]

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