A vessel contains a mixture of H₂ and D₂ gases. If a pin hole is made in the vessel, then — States of Matter and Gaseous State Chemistry Question

💡 Solution & Explanation

By Graham's Law, the rate of effusion is inversely proportional to the square root of molar mass ($r \propto 1/\sqrt{M}$). H₂ ($M=2$) effuses faster than D₂ ($M=4$). Because H₂ escapes faster, the remaining gas mixture becomes relatively richer in D₂. Thus, the mole fraction of D₂ increases, and the average molecular weight of the remaining gas increases. Both partial pressures will decrease as gas escapes. Therefore, correct answer is B,C.