J & K CET Medical J & K - CET Medical Solved Paper-2002

  • question_answer
    At what temperature is rms : molecules double of that at NTP

    A) \[819{}^\circ C\]

    B) \[719{}^\circ C\]

    C) \[909{}^\circ C\]         

    D) none of these

    Correct Answer: A

    Solution :

    Root mean square velocity is \[{{v}_{rms}}=\sqrt{\frac{3RT}{M}}\] where R is gas constant, T the absolute temperature and M the molecular weight. \[\Rightarrow \]               \[\frac{{{v}_{1}}}{{{v}_{2}}}=\sqrt{\frac{{{T}_{1}}}{{{T}_{2}}}}\] Given, \[{{v}_{1}}:{{v}_{2}}=1:2,\]            \[{{T}_{1}}=273\,K\] \[\therefore \]  \[\frac{1}{2}=\sqrt{\frac{273}{{{T}_{2}}}}\] \[\Rightarrow \]               \[{{T}_{2}}=4\times 273=1092K\] In centigrade \[{{T}_{2}}={{(1092-273)}^{o}}C={{819}^{o}}C\]


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