Which of the following is a non-electrolyte?

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

The freezing point of a $1.00 \ m$ aqueous solution of $HF$ is found to be $-1.91 \ ^oC$. The freezing point constant of water,$K_f$ is $1.86 \ K \ kg \ mol^{-1}$. The percentage dissociation of $HF$ at this concentration is ................ $\%$

Which of the following has the highest boiling point?

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 $.0$)

Which one of the following electrolytes has the same value of van't Hoff factor $(i)$ as that of $Al_2(SO_4)_3$ (if all are $100 \%$ ionised)?