The mean free path of molecules of a gas at STP is 1500d, where d is the molecular diameter. At the same pressure, the mean free path at 373 K is approximately:
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Question

The mean free path of molecules of a gas at STP is 1500d, where d is the molecular diameter. At the same pressure, the mean free path at 373 K is approximately:

G1 Physics · Accepted Answer

Mean free path of a gas is λ = RT/(√2 πd²NₐP) At constant pressure, λ ∝ T At STP, T₁ = 273 K and λ₁ = 1500d Thus, λ₂/λ₁ = 373/273 λ₂ = 1500d × 373/273 ≈ 2049d Hence option D follows.