JEE Main & Advanced Sample Paper JEE Main - Mock Test - 40

  • question_answer
    A gas mixture consists of molecules of type 1,2 and 3, with molar masses \[{{m}_{1}}>{{m}_{2}}>{{m}_{3}}.\text{ }{{V}_{rms}}\] and \[\overline{K}\] are the r.m.s. speed and average kinetic energy of the gases. Which of the following is true-

    A) \[{{\left( {{V}_{rms}} \right)}_{1}}<{{\left( {{V}_{rms}} \right)}_{2}}<{{\left( {{V}_{rms}} \right)}_{3}}\And {{\left( \overline{K} \right)}_{1}}={{\left( \overline{K} \right)}_{2}}={{\left( \overline{K} \right)}_{3}}\]

    B) \[{{\left( {{V}_{rms}} \right)}_{1}}={{\left( {{V}_{rms}} \right)}_{2}}={{\left( {{V}_{rms}} \right)}_{3}}\And {{\left( \overline{K} \right)}_{1}}={{\left( \overline{K} \right)}_{2}}>{{\left( \overline{K} \right)}_{3}}\]

    C) \[{{\left( {{V}_{rms}} \right)}_{1}}>{{\left( {{V}_{rms}} \right)}_{2}}>{{\left( {{V}_{rms}} \right)}_{3}}\And {{\left( \overline{K} \right)}_{1}}<{{\left( \overline{K} \right)}_{2}}>{{\left( \overline{K} \right)}_{3}}\]

    D) \[{{\left( {{V}_{rms}} \right)}_{1}}>{{\left( {{V}_{rms}} \right)}_{2}}>{{\left( {{V}_{rms}} \right)}_{3}}\And {{\left( \overline{K} \right)}_{1}}<{{\left( \overline{K} \right)}_{2}}<{{\left( \overline{K} \right)}_{3}}\]

    Correct Answer: A

    Solution :

    [a] \[{{V}_{rms}}\propto \frac{1}{\sqrt{M}}\Rightarrow \left( {{V}_{rms}} \right)<{{\left( {{V}_{rms}} \right)}_{2}}<{{\left( {{V}_{rms}} \right)}_{3}}\] also in mixture temperature of each gas will be same, hence kinetic energy also remains same.


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