KVPY Sample Paper KVPY Stream-SX Model Paper-16

  • question_answer
    An ideal gas is adiabatically compressed to one tenth of its initial volume. Ratio of final temperatures \[{{T}_{A}}\] and \[{{T}_{B}}\] will be (where, in case A a monoatomic gas is taken and in case B a diatomic gas is taken)

    A) \[\frac{{{T}_{A}}}{{{T}_{B}}}={{10}^{\frac{7}{5}}}\]

    B) \[\frac{{{T}_{A}}}{{{T}_{B}}}={{10}^{\frac{2}{5}}}\]

    C) \[\frac{{{T}_{A}}}{{{T}_{B}}}={{10}^{\frac{4}{15}}}\]

    D) \[\frac{{{T}_{A}}}{{{T}_{B}}}={{10}^{\frac{7}{15}}}\]

    Correct Answer: C

    Solution :

    For adiabatic process,
    \[{{T}_{i}}{{V}_{i}}^{\gamma -1}={{T}_{f}}V_{f}^{\gamma -1}\Rightarrow \frac{{{T}_{f}}}{{{T}_{i}}}={{\left( \frac{{{V}_{i}}}{{{V}_{f}}} \right)}^{\gamma -1}}\]
    Here, \[\frac{{{V}_{i}}}{{{V}_{f}}}=10\]
    So, \[{{T}_{f}}={{T}_{i}}{{(10)}^{\gamma -1}}\]
    For monoatomic gas, \[\gamma =\frac{5}{3}\]and for diatomic gas,  and for \[\gamma =\frac{7}{5}.\]          
    Hence, \[\frac{{{T}_{A}}}{{{T}_{B}}}=\frac{{{10}^{\frac{5}{3}-1}}}{{{10}^{\frac{7}{5}-1}}}={{10}^{\frac{4}{15}}}\]


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