The compressibility factor for a real gas at high pressure is :

'a’ and `b’ are van der Waals’ constants for gases. Chlorine is more easily liquefied than ethane because

If 10^–4 dm³ of water is introduced into a 1.0 dm³ flask to 300 K, how many moles of water are in the vapour phase when equilibrium is established ?
(Given : Vapour pressure of H₂O at 300 K is 3170 Pa ; R = 8.314 J K^–1 mol^–1)

Equal masses of methane and oxygen are mixed in an empty container at 25^oC. The fraction of the total pressure exerted by oxygen is