Mass of Urea $(NH_2CONH_2)$ required to be dissolved in $1000 \ g$ of water to reduce the vapour pressure of water by $25 \ \%$ is $...... \ g$. (Nearest integer) Given: Molar mass of $N, C, O$ and $H$ are $14, 12, 16$ and $1 \ g \ mol^{-1}$ respectively.

$A$ solution contains $KCl$ in water. It is heated continuously and the vapour formed is removed continuously. The vapour pressure of the solution will be:

The vapour pressure of pure benzene and methyl benzene at $27^{\circ} C$ is given as $80 \ Torr$ and $24 \ Torr$,respectively. The mole fraction of methyl benzene in vapour phase,in equilibrium with an equimolar mixture of those two liquids (ideal solution) at the same temperature is. . . . . . .$\times 10^{-2}$ (nearest integer)

The vapour pressure of pure liquids $A$ and $B$ are $450$ $mm$ $Hg$ and $700$ $mm$ $Hg$ respectively,at $350$ $K$. Find out the composition of the liquid mixture if the total vapour pressure is $600$ $mm$ $Hg$. Also,find the composition of the vapour phase.

The relative lowering of vapour pressure produced by dissolving $71.5 \ g$ of a substance in $1000 \ g$ of water is $0.00713$. The molecular weight of the substance will be:

The following graph is obtained for an ideal solution containing a non-volatile solute. The $x$- and $y$-axes represent,respectively: