Which of the following solutions has the lowest freezing point?

$AB_2$ is $10\%$ dissociated in water to $A^{2+}$ and $B^{-}$. The boiling point of a $10.0 \text{ molal}$ aqueous solution of $AB_2$ is . . . . . . $^\circ C$. (Round off to the Nearest Integer). [Given: Molal elevation constant of water $K_b = 0.5 \text{ K kg mol}^{-1}$,boiling point of pure water $= 100^\circ C$]

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

At $25 \ ^oC$,the highest osmotic pressure is exhibited by $0.1 \ M$ solution of

In an aqueous solution of $NaCl$,the mole fraction of the solvent is $0.9$. Then,the relative lowering in vapour pressure will be ......... $atm$.

The freezing point of a $0.2 \ m$ aqueous solution of a weak acid $(HX)$ which is $20\%$ ionized is ......... $^oC$. (Given: $K_f = 1.86 \ ^oC/m$ for water)