Which of the following solutions has the lowest freezing point?

For a $0.2 \ m$ aqueous solution of a weak acid $HX$,the degree of ionization is $0.3$. If $K_f$ for water is $1.85 \ K \ kg \ mol^{-1}$,the freezing point of the solution will be close to .......... $^oC$.

Which of the following solutions will have the highest boiling point?

$0.1 \ m$ solutions of sodium sulphate,urea,and sodium chloride are taken. The correct ratio of the elevation of boiling point of these solutions is

The measured osmotic pressure of a solution prepared by dissolving $17.4 \ mg$ of $K_2SO_4$ in $2 \ L$ of water at $27^{\circ} C$ is $3.735 \times 10^{-3} \ bar$. The van't Hoff factor is $(R = 0.083 \ L \ bar \ K^{-1} \ mol^{-1}$; atomic weights $K = 39, S = 32, O = 16)$.

Calculate the amount of $KCl$ $(M_w = 74.5 \ g \ mol^{-1})$ in grams required to depress the freezing point of $1000 \ g$ of water by $2 \ K$. (Given: $K_f = 1.86 \ K \ kg \ mol^{-1}$) (in $.0$)