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

$A$ solution of $CaCl_2$ is prepared by dissolving $0.0112 \ g$ of $CaCl_2$ in $1 \ kg$ of distilled water. If the molal freezing point depression constant $(K_f)$ of water is $2 \ K \ kg \ mol^{-1}$,what is the depression in the freezing point of the solution? (Assume $100\%$ ionization of $CaCl_2$)

$pH$ 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 will have the highest depression in freezing point when their concentration is $0.1 \ M$?

Which of the following is a non-electrolyte?

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