# Vapour pressure of chloroform $(CHCl_3$) and dichloromethane ($CH_2Cl_2$) at 298 K are 200 mm Hg and 415 mm Hg respectively. (ii) mole fractions of each component in vapour phase.

Calculation of mole fraction in vapour phase
To calculate the same, we need to first find the partial pressure of each component.
$P_{CH_2Cl_2} = 0.688 \times 415 mm$ Hg = 285.5 mm Hg
$P_{CHCl_3} = 0.312 \times 200$ mm Hg = 62.4 mm Hg
We also know that in vapour phase
$P_A = Y_AP_T$
Applying the above equation, we get
$Y_{CH_2Cl_2}$ = 285.5 mm Hg/347.9 mm Hg = 0.82
$Y_{CHCl_3}$= 62.4 mm Hg/347.9 mm Hg = 0.18
Hence (A) is the correct answer.