Which of the following has the same van't Hoff factor $(i)$ as $K_3[Fe(CN)_6]$?

Which one of the following is the ratio of the lowering of vapour pressure of $0.1 \ M$ aqueous solutions of $BaCl_2, NaCl$ and $Al_2(SO_4)_3$ respectively?

The Van't Hoff factor will be highest for

$A$ $0.2 \, m$ aqueous solution of a weak acid $(HX)$ is $20 \%$ ionised. The freezing point of this solution is .......... $^oC$. ($K_f = 1.86 \, K \cdot kg \cdot mol^{-1}$ for water) :-

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

The Van't Hoff factor for a $0.005 \ M$ aqueous solution of $KCl$ is $1.95$. The degree of ionisation of $KCl$ is