# The molar volume of liquid benzene (density = 0.877 $g mL^{-1}$) increases by a factor of 2750 as it vapourises at $20^{\large\circ}$C and that of liquid toluene (density = 0.867 $g mL^{-1}$) increases by a factor of 7720 at 20$^{\large\circ}$C. A solution of benzene and toluene at 20$^{\large\circ}$C has a vapour pressure of 46.0 Torr. Find the mole fraction of benzene in the vapour above the solution.

0.73
Hence (D) is the correct answer.