At , the root mean square () speed of a gas X (molecular weight ) is exactly equal to the most proba — States of Matter and Gaseous State Chemistry Question

💡 Solution & Explanation

Equating the expressions: $U_{rms}(X) = U_{mp}(Y) \implies \sqrt{3RT_X / M_X} = \sqrt{2RT_Y / M_Y}$. Substituting values: $\sqrt{3R(400) / 40} = \sqrt{2R(60) / M_Y}$. Squaring and simplifying: $30 \times R = 120 \times R / M_Y \implies 30 = 120 / M_Y \implies M_Y = 120 / 30 = 4\text{ g/mol}$.