If two substances A and B have `p_(A)^(@): p_(B)^(@) = 1:2` and have mole fraction in solution as 1:2 then mole fraction of A in vapour phase is

Options

A. 0.33
B. 0.25
C. 0.52
D. 0.2

Answer

D

Explanation

Mole fraction of component 'A' in vapour phase
`=(p_(A))/(p_(A)+p_(B))`
`"but "p_(A)=p_(A)^(@)x_(A)andp_(B)=p_(B)^(@)x_(B)=(p_(A)^(@)x_(A))/(p_(A)^(@)x_(A)+p_(B)^(@)x_(B))`
Mole fraction of component 'A' in vapour phase
`=(1xx1)/(1xx1+2xx2)=0.2`