Molar mass of $CH_2Cl_2\,=\,85\,g/mol.$

Molar of $CHCl_3\,=\,\frac {11.95}{119.5}\,=\,0.1\,mol.$

Molar of $CH_2Cl_2\,=\,\frac {8.5}{85}\,=\,0.1\,mol.$

Mole fraction of $CHCl_3\,=\,\frac {0.1}{0.2}\,=\,0.5\,mol$

Mole fraction of $CH_2Cl_2\,=\,\frac {0.1}{0.2}\,=\,0.5\,mol$

(Given-

Vapour pressure of $CHCl_3\,=\,200\,mm$  $Hg\,=\,0.263\,atm$.

Vapour pressure of $CH_2Cl_2\,=\,415\,mm$  $Hg\,=\,0.546\,atm$.)

$(1\,atm\,=\,760\,mm\,Hg)$

$\therefore P_{(abovesolution)}$ $=$ Mole fractiion of $CHCl_3\times $ (Vapour pressure of $CHCl_3$ ) $+$ Mole fractiion of $CH_2Cl_2\times $ (Vapour pressure of $CH_2Cl_2$ )

$=\,0.5\times 0.263\,+\,0.5\times 0.546\,=\,0.4045$

Mole fraction of $CHCl_3$ in vapour form

$=\,\frac {0.1315}{0.4045}\,=\,0.325$