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

Two liquids $A$ and $B$ have vapour pressure in the ratio $P_A^o : P_B^o = 1 : 3$ at a certain temperature. If the ratio of mole fractions of $A$ to $B$ in the vapour phase is $4 : 3$,then the mole fraction of $B$ in the solution at the same temperature is

$100 \, g$ of liquid $A$ (molar mass $140 \, g \, mol^{-1}$) was dissolved in $1000 \, g$ of liquid $B$ (molar mass $180 \, g \, mol^{-1}$). The vapour pressure of pure liquid $B$ was found to be $500 \, torr$. Calculate the vapour pressure of pure liquid $A$ and its vapour pressure in the solution if the total vapour pressure of the solution is $475 \, torr$.

Vapour pressure of solvent is $17.5 \ mm \ Hg$ while that of dilute solution is $17.45 \ mm \ Hg$; the mole fraction of solvent is

Two open beakers,one containing a solvent and the other containing a mixture of that solvent with a non-volatile solute,are together sealed in a container. Over time:

If $Raoult's$ law is obeyed,the vapor pressure of the solvent in a solution is proportional to which of the following?