Q3 / 180 · KCET 2013 · Chemistry

Which of the following gases has the highest value of RMS velocity at $298 \mathrm{~K}$ ?

  • Correct answer
    A
    $\mathrm{CH}_{4}$
  • B
    $\mathrm{CO}$
  • C
    $\mathrm{Cl}_{2}$
  • D
    $\mathrm{CO}_{2}$

Solution

RMS-velocity of a gas $v_{\text {rms }}=\sqrt{\frac{3 R T}{M}}$ Hence, higher the molecular weigth of a gas, lower will be its RMS-velocity $v_{\text {rms }} \propto \sqrt{\frac{1}{M}}$ $\therefore \mathrm{CH}_{4}$ (mol. weight $=16$ ) has highest RMS-velocity.

Hence, the correct answer is option: 'A'.

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