The vapour pressure of pure liquid solvent A is `0.80`atm.When a non volatile substances B is added to the solvent, its vapour pressure drops to `0.60`atm. Mole fraction of the components B in the solution is:

Options

A. `0.50`
B. `0.25`
C. `0.75`
D. `0.40`

Answer

B

Explanation

Acc . To R.L V.P `rArr X_(B)`
`x_(B) = (0.80 - 0.60 )/(0.80 ) = (0.20)/(0.80) = 0.25` .