NEET Physics Kinetic Theory of Gases NEET PYQ-Kinetic Theory Of Gases

  • question_answer
               
    At what temperature will the rms speed of oxygen molecules become just sufficient for escaping from the Earth's atmosphere?
    (Given :                                    [NEET - 2018]
    Mass of oxygen molecule \[\text{(m)=2}\text{.76 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{--26}}}\text{kg}\]
    Boltzmann's constant \[{{\text{k}}_{\text{B}}}\text{=1}\text{.38 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{--23}}}\text{J}{{\text{K}}^{\text{--1}}}\text{)}\]

    A)  \[\text{5}\text{.016 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{4}}}\text{ K}\]

    B)       \[\text{8}\text{.360 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{4}}}\text{ K}\]

    C)  \[\text{2}\text{.508 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{4}}}\text{ K}\]

    D)       \[\text{1}\text{.254 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{4}}}\text{ K}\]

    Correct Answer: B

    Solution :

    [b] \[{{\text{V}}_{\text{escape}}}\text{=11200 m/s}\]
    Say at temperature T it attains \[{{\text{V}}_{\text{escape}}}\]
    So, \[\sqrt{\frac{\text{3}{{\text{k}}_{\text{B}}}\text{T}}{{{\text{m}}_{{{\text{O}}_{\text{2}}}}}}}=11200m/s\]
    On solving,
    \[\text{T=8}\text{.360 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{4}}}\text{ K}\]


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