400cm3 of a gas at 500 mm pressure is increased to 800cm3. Taking the temperature to remain unchanged, find the decrease in pressure.
Vapour pressure of pure A is (P∘A)=100 mm Hg. Vapour pressure of pure B is (P∘B)=150 150mm Hg. If 2 moles of A and 3 moles of B are mixed to form ideal solution, the vapour pressure of solution will be