JEE Main & Advanced Physics Kinetic Theory of Gases Question Bank Self Evaluation Test - Kinetic Theory

  • question_answer
    The absolute gas temperature at which the root mean square speed of helium molecules exceeds their most probable speed by 200 m/s is

    A) 110.2 K

    B) 90.2 K

    C) 190.2 K

    D) 100.2 K

    Correct Answer: C

    Solution :

    [c] If T be the required temperature, then, \[{{v}_{rms}}-{{v}_{p}}=200m/s\] \[\text{or }\sqrt{\frac{3RT}{{{M}_{He}}}}-\sqrt{\frac{2RT}{{{M}_{He}}}}=200m/s\] \[\text{or }\sqrt{T}\text{ }\left[ \sqrt{3}-\sqrt{2} \right]=\sqrt{\frac{{{M}_{He}}}{R}}\left( 200m/s \right)\]  Substituting \[{{M}_{He}}=4\times {{10}^{-3}}kg,\,R=8.134\,J/mol-K,\] \[T=190.2K.\]


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