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 46 g of toluene in torr is
(a) 50
(b) 25
(c) 37.5
(d) 53.5
