Statement I: The average speed of gas molecules decreases with the increase in molar mass of gas at — States of Matter and Gaseous State Chemistry Question

💡 Solution & Explanation

Average speed is c_avg = √(8RT/πM), which decreases as molar mass M increases (Statement I is correct). Since all gases at the same temperature have the same average kinetic energy (1.5 RT), the heavier molecules must move slower to maintain the same kinetic energy. Thus, Statement II explains Statement I.