NEET Sample Paper NEET Sample Test Paper-15

  • question_answer 70 calories of heat are required to raise the temperature of 2 moles of an ideal gas at constant pressure from \[30{}^\circ C\] to \[35{}^\circ C\]. The amount of heat required (in calories) to raise the temperature of the same gas through the same range (\[30{}^\circ C\] to \[35{}^\circ C\]) at constant volume is

    A)  30                 

    B)  50

    C)  70                 

    D)  90

    Correct Answer: B

    Solution :

    Invoking first law of Thermodynamics for constant pressure process, we get \[\Delta Q=\Delta U+\Delta W\] \[70=\Delta U+nR\Delta T\] \[70=\Delta U+2\times 2\times 5\] \[\therefore \]    \[\Delta U=70-20=50\,\]calories For constant volume process:\[\Delta Q=\Delta U+\Delta W\] \[\Delta U\]will remain 50 calories because the temperature change is same and \[\Delta W\]will be 0 for constant volume process. \[\therefore \]\[\Delta Q=50\]calories Hence, the correction option is [b].

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