Why does the insolubility of benzene and water in each other cause each liquid to exert its own vapor pressure when a mixture of benzene and water undergo steam distillation?

Explanation: Water and Benzene are insoluble in each other. The molecules in a drop of benzene are not diluted by water molecules from nearby water droplets due to steam distillation so each liquid would exert its own vapor pressure. two liquids exert pressure against external pressures independently