Which of the following solutions will show the maximum depression in freezing point when the concentration is $0.1 \, M$?

For a dilute solution of $K_3[Fe(CN)_6]$,the van't Hoff factor $(i)$ is ..... [assuming $100\%$ ionization]

The osmotic pressure of equimolar solutions of urea,$BaCl_2$,and $AlCl_3$ will be in the order:

The correct order of boiling point of the given aqueous solutions is:

Of the following four aqueous solutions,the total number of those solutions whose freezing point is lower than that of $0.10 \, M \, C_{2}H_{5}OH$ is (Integer answer).
$(i)$ $0.10 \, M \, Ba_{3}(PO_{4})_{2}$
$(ii)$ $0.10 \, M \, Na_{2}SO_{4}$
$(iii)$ $0.10 \, M \, KCl$
$(iv)$ $0.10 \, M \, Li_{3}PO_{4}$

$0.5 \text{ molal}$ aqueous solution of a weak acid $(HX)$ is $20\%$ ionised. If $K_f$ for water is $1.86 \ K \ kg \ mol^{-1}$,the depression in freezing point of the solution is $......... \ K$.