KVPY Sample Paper KVPY Stream-SX Model Paper-15

  • question_answer
    A mixture of ideal gas containing 5 moles of monoatomic gas and 1 mole of rigid diatomic gas is initially at pressure \[{{\text{P}}_{0.}}\]volume \[{{\text{V}}_{0}}\] and temperature \[{{T}_{0.}}\] If the gas mixture is adiabatically compressed to a volume \[{{\text{V}}_{\text{0}}}\text{/}4,\] then the correct statement(s) is/are: (\[\text{given}\,{{2}^{1.2}}\,=\,2.3;\,{{2}^{3.2}}=\,9.2;\,\text{R}\,\]is gas constant)

    A) Adiabatic constant of the gas mixture is 1.6

    B) The average kinetic energy of the gas mixture after compression is in between \[18\text{R}{{\text{T}}_{0}}\] and \[19\text{R}{{\text{T}}_{0.}}\]

    C) The final pressure of the gas mixture after compression is in between \[9{{\text{P}}_{0}}\] and \[10{{\text{P}}_{0}}.\]

    D) The work \[\left| \,\text{W}\, \right|\]done during the process is \[13\text{R}{{\text{T}}_{0}}.\]

    Correct Answer: A , C , D

    Solution :

    monoatomic  \[\left. \begin{align}   & \text{monoatomic}\,\,\,\text{(5moles)} \\  & \,\,\,\,\text{diatomic}\,\,\,\,\,\,\,\,\,\,\,\text{(Imole)} \\ \end{align} \right\}{{\text{P}}_{0}},\,\,{{\text{V}}_{0,\,\,}}{{\text{T}}_{0}}\]
    adiabtically compression to \[\frac{{{\text{V}}_{0}}}{4}\]
                \[{{\gamma }_{mix}}=\frac{{{n}_{1}}{{C}_{p1}}+{{n}_{c}}{{C}_{{{p}_{z}}}}}{{{n}_{1}}{{C}_{{{Y}_{1}}}}+{{n}_{2}}{{C}_{{{V}_{2}}}}}=\frac{8}{5}\]           
                \[\text{W}=\frac{{{P}_{1}}{{V}_{1}}-{{P}_{2}}{{V}_{2}}}{\gamma -1}\].
    and       \[{{\text{p}}_{0}}{{\text{V}}_{0}}^{\text{8/5}}=\,{{\text{p}}_{2}}{{\left( \frac{{{\text{V}}_{0}}}{4} \right)}^{\text{8/5}}}\]
    \[\therefore \]      \[{{\text{P}}_{2}}=9.2{{\text{P}}_{0}}\]
    \[\therefore \]      \[\text{W}=\,\frac{{{\text{P}}_{0}}{{\text{V}}_{0}}-(9.2{{P}_{0}})({{\text{V}}_{0}}/4)}{3/5}\,=-13\text{R}{{\text{T}}_{0}}\]
                            \[\left| \text{W} \right|\,=\,13\text{R}{{\text{T}}_{0}}.\]

    Solution :

    Same as above

    Solution :

    Same as above


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