An aqueous solution which contains $42 \%$ by weight $(\mathrm{w} / \mathrm{W})$ of a volatile liquid "A" of molar mass of $140 \mathrm{~g} / \mathrm{mol}$, has a vapour pressure of 2141.4 mm of Hg at $37^{\circ} \mathrm{C}$. What is the vapour pressure of the pure liquid " A "? Vapour pressure of water at $37^{\circ} \mathrm{C}$ is 2019.1 mm .

A dilute solution of $\mathrm{K}_2 \mathrm{HgI}_4$ reagent is $95 \%$ ionised. What would be the approximate value of its van't Hoff factor?

When $0.4 \mathrm{~g} \mathrm{CH}_3 \mathrm{COOH}$ is added to 40 g of Benzene to form a solution, the freezing point is depressed by $0.45^{\circ} \mathrm{C}$. If Acetic acid undergoes dimerisation in Benzene ( $\mathrm{K}_{\mathrm{f}}=5.12 \mathrm{~K} \mathrm{~kg} / \mathrm{mol}$ ) what is the percentage association of the acid in Benzene?

A dilute solution of an ionic compound $\mathrm{A}_3 \mathrm{~B}$ has an Osmotic pressure which is 6 times that of $0.02 \mathrm{M} \mathrm{MgCl}_2$. What is the molar concentration of $\mathrm{A}_3 \mathrm{~B}$ assuming that it undergoes complete dissociation in water?