Benzene and toluene form nearly ideal solution. 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 in a solution containing 78 g of benzene and 46 g of toluene in torr is
a) 50.0
b) 25.0
c) 37.5
d) 53.5
