Q38 · CSIR-NET Chemistry, June 2011

Paper: CSIR-NET June 2011 · Subject: Physical Chemistry · Chapter: Gaseous State · Topic: Gaseous State – General · Marks: 2 · Difficulty: Medium

For an assembly of molecules (molar mass $=M$) at temperature $T$, the standard deviation of Maxweller's speed is approximately

(a)$0.7 \sqrt{\frac{R T}{M}}$

(b)$1.4 \sqrt{\frac{R T}{M}}$

(c)$0.7 \sqrt{\frac{M}{R T}}$

(d)$1.4 \sqrt{\frac{M}{R T}}$

Answer

Answer: A ✓ checked by 4AB · confidence high

Explanation

σ = √(⟨v²⟩ − ⟨v⟩²) = √(3RT/M − 8RT/πM) = √(0.454 RT/M) ≈ 0.67√(RT/M) ≈ 0.7√(RT/M) (a).

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