Which of the following statement(s) is(are) correct regarding the root mean square speed ($U_{rms}$) and average translational kinetic energy $\left(\varepsilon_{av}\right)$ of a molecule in a gas at equilibrium ?
$U_{rns}$ is doubled when its temperature is increased four times
$\varepsilon_{av}$ is doubled when its temperature is increased four times
$\varepsilon_{av}$ at a given temperature does not depend on its molecular mass
$U_{rns}$ is inversely proportional to the square root of its molecular mass
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The Correct Option isD
Solution and Explanation
$\bar{E}_{K} = \frac{3}{2}KT$ Average kinetic energy depends only on absolute temperature K = Boltzmann constant $U_{rms} = \sqrt{\frac{3RT}{M}}$ $U_{rms} \propto \sqrt{T}$ $U_{rms} \propto \frac{1}{\sqrt{M}}$ Using above formulae, correct statements are (A, C, D).