Benzene and toluene form nearly ideal solutions. At `20^@C` the vapour pressure of benzene is 75 torr and that of toluene is 22 torr. The partial vapour pressure of benzene at 20°C for a solution containing 78g of benzene and 46g of toluene in torr is:

Options

A. 25
B. 50
C. `53.5`
D. `37.5`

Answer

B

Explanation

Benzene: A, Tolvene: B
`X_(A) = (1)/(1+0.5) = (1)/(3//2) = (2)/(3)`
`P_(A) = P_(A)^(@) X_(A) = 75 xx (2)/(3) = 50` torr