The vapour pressures of pure benzene and toluene are 160 and 60mm Hg respectively. The mole fraction of benzene is vapour phase in contact with equimolar solution of benzene and toluene is

Options

A. `0. 0 73`
B. `0. 0 27`
C. `0. 27`
D. `0. 73`

Answer

D

Explanation

`P _(T) = 160 xx (1)/(2) 60 xx (1)/(2) = 110`
`P _(B) = P _(B) ^(@) xx B = 160 xx (1)/(2)`
`P _(B) = P _(T) X _(B) implies 80 = 110 Y _(B)`
`Y _(B) = ( 80)/(110 ) = 0. 73`