The vapour pressure of water at $20\,^{\circ}C$ is $17.54\,mm$. When $20\,g$ of a non-ionic substance is dissolved in $100\,g$ of water,the vapour pressure is lowered by $0.30\,mm$. What is the molecular weight of the substance?

The vapor pressure of a liquid mixture of $X$ and $Y$ is given by the equation $P = 160X_x + 50$,where $X_x$ is the mole fraction of $X$. The ratio of the vapor pressures of pure liquids $X$ and $Y$ is:

The vapor pressure of water at a certain temperature is $3000 \ N \ m^{-2}$. When a non-electrolyte solute is added,it decreases by $300 \ N \ m^{-2}$. The molality of the solution is ............. $m$.

Calculate the mass of a non-volatile solute (molar mass $40 \, g \, mol^{-1}$) which should be dissolved in $114 \, g$ octane to reduce its vapour pressure to $80 \%$.

The vapour pressure of pure liquids $A$ and $B$ are $450 \ mm$ and $700 \ mm$ of $Hg$ at $350 \ K$ respectively. If the total vapour pressure of the mixture is $600 \ mm$ of $Hg$,the composition of the mixture in the solution is

Vapour pressure of pure benzene is $119 \ torr$ and that of toluene is $37.0 \ torr$ at the same temperature. The mole fraction of toluene in the vapour phase,which is in equilibrium with a solution of benzene and toluene having a mole fraction of toluene $0.50$,will be: