Equal-volume vessels contain neon (monoatomic), chlorine (diatomic) and uranium hexafluoride (polyatomic) at the same temperature and pressure. Choose the correct order of their rms speeds.
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Question

Equal-volume vessels contain neon (monoatomic), chlorine (diatomic) and uranium hexafluoride (polyatomic) at the same temperature and pressure. Choose the correct order of their rms speeds.

G1 Physics · Accepted Answer

At the same temperature, v(rms) = √(3RT/M), so v(rms) ∝ 1/√M. M(Ne) < M(Cl₂) < M(UF₆), hence v(Ne) > v(Cl₂) > v(UF₆).