24. Liquids A and B form an ideal solution. At a certain temperature the total vapour pressure of a mixture of A and B is 400 mm. The mole fraction of A in the liquid mixture in equilibrium with the vapour phase is
0.4. If the vapour pressure ratio (P)/ P) for the pure liquids at this temperature is 1/6, what is the
partial pressure of A in the vapour phase?
(A) 50mm
(B) 60mm
(C) 70mm
(D) 40mm