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MHT CET 2020 (19 Oct, Shift 2) · Molecular Speeds & Maxwell Distribution

Molecular Speeds & Maxwell Distribution question from MHT CET 2020 (19 Oct, Shift 2)

Q72MHT CET 2020 · 19 OCT · SHIFT 2Medium

Molecular Speeds & Maxwell Distribution

The root mean square velocity of molecules of a gas is 200 m/s200\text{ m/s}. What will be the root mean square velocity of the molecules, if the molecular weight is doubled and the absolute temperature is halved?

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Answer: (c)

  1. vrms∝TMv_{rms} \propto \sqrt{\frac{T}{M}}
  2. T→T2T \to \frac{T}{2}, M→2MM \to 2M: TM→14⋅TM\frac{T}{M} \to \frac{1}{4}\cdot\frac{T}{M}, so vrmsv_{rms} halves
  3. v′=2002=100 m/sv' = \frac{200}{2} = 100\text{ m/s}
  4. So the answer is (c) 100 m/s100\text{ m/s}.
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