NEET Sample Paper NEET Sample Test Paper-70

  • question_answer
    For two gases A and B with molecular weights\[{{M}_{A}}\,\,and\text{ }{{M}_{B}}\], it is observed that at a certain temperature\[{{T}_{1}}\]; the mean velocity of A is equal to the root mean square velocity of B. Thus the mean velocity of A can be made equal to the mean velocity of B if

    A) A is at temperature T and B at \[\operatorname{T}, T> T\]

    B) A is lowered to a temperature \[{{\operatorname{T}}_{2}}, {{T}_{2}}< T\] while B is at T

    C) Both A and B are raised to a higher temperature

    D) Both A and B are placed at lower temperature

    Correct Answer: B

    Solution :

    \[{{\left( {{U}_{AV}} \right)}_{A}}=\sqrt{\frac{8\,RT}{\pi {{M}_{A}}}}\,\,and\,\,{{\left( {{U}_{rms}} \right)}_{B}}=\sqrt{\frac{3RT}{{{M}_{B}}}}\] \[\therefore \,\,\,\,\,\,\,\,\frac{8}{3\pi }=\frac{{{M}_{A}}}{{{M}_{B}}}\] \[A\left( {{U}_{AV}} \right)=\sqrt{\frac{8\,R{{T}_{2}}}{\pi {{M}_{A}}}}\,\,for\,\,B\,\,{{V}_{AV}}=\sqrt{\frac{8RT}{\pi \,{{M}_{B}}}}\] \[\frac{{{T}_{2}}}{T}=\frac{{{M}_{A}}}{{{M}_{B}}}=\frac{8}{3\pi }\] \[\therefore \,\,\,\,\,\,{{T}_{2}}=\frac{8}{3\pi }T\,\,\,\,or\,\,\,{{T}_{2}}<T\,\,\,\]


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