Mole fraction of vapour of `A` above solution in mixture of `A` and `B(X_(A) = 0.4)` will be `(P_(A)^(@) = 100mm, P_(B)^(@) = 200 mm)`:

Options

A. 0.4
B. 0.25
C. 0.85
D. None of these

Answer

B

Explanation

Mole fraction of A in vapour phase
`=(p_(A)^(@)x_(A))/(p_("Total"))=(100xx10^(0.4))/(100xx4+200xx0.6)=0.25`