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JEE Main 2023 (13 Apr, Shift 1) · Molecular Speeds & Maxwell Distribution

Molecular Speeds & Maxwell Distribution question from JEE Main 2023 (13 Apr, Shift 1)

Q43JEE Main 2023 · 13 APR · SHIFT 1Medium

Molecular Speeds & Maxwell Distribution

The rms speed of oxygen molecule in a vessel at particular temperature is (1+5x)12v\left(1 + \frac{5}{x}\right)^{\frac{1}{2}} v, where vv is the average speed of the molecule. The value of xx will be:

(( Take π=227)\pi = \frac{22}{7})

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Answer: (c)

  1. vrms=3RTMv_{rms} = \sqrt{\frac{3RT}{M}}, vav=8RTπMv_{av} = \sqrt{\frac{8RT}{\pi M}}, so vrms2vav2=3π8\frac{v_{rms}^2}{v_{av}^2} = \frac{3\pi}{8}
  2. With π=227\pi = \frac{22}{7}: 3π8=6656=3328=1+528\frac{3\pi}{8} = \frac{66}{56} = \frac{33}{28} = 1 + \frac{5}{28}
  3. So x=28x = 28; the answer is (c) 28.
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