35.0 torr and 0.480
30.5 torr and 0.389
38.0 torr and 0.589
35.8 torr and 0.280
The mole fraction of benzene is χB = 1.5/(1.5 + 3.5) = 0.3
The partial pressure of benzene is PB = 0.3 × 74.7 = 22.4 torr
The partial pressure of toluene is χT = 0.7 × 22.3 = 15.6 torr
The total pressure is PT = 22.4 + 15.6 = 38.0 torr
The mole fraction of benzene in vapor is Y = 22.4/38.0 = 0.589.
Hence, the correct option is C