If the rms speed of chlorine molecules is 490 m s⁻¹ at 27°C, the rms speed of argon molecules at the same temperature is: (atomic mass of Ar = 39.9 u, molecular mass of Cl₂ = 70.9 u)
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Question

If the rms speed of chlorine molecules is 490 m s⁻¹ at 27°C, the rms speed of argon molecules at the same temperature is: (atomic mass of Ar = 39.9 u, molecular mass of Cl₂ = 70.9 u)

G1 Physics · Accepted Answer

At the same temperature, vᵣₘₛ = √(3RT/M) Therefore, vₐᵣ / v꜀ₗ₂ = √(M꜀ₗ₂ / Mₐᵣ) = √(70.9/39.9) ≈ 1.33 Hence, vₐᵣ ≈ 1.33 × 490 ≈ 651.7 m s⁻¹ Hence option C follows.