KVPY Sample Paper KVPY Stream-SX Model Paper-15

  • question_answer
    A gas can be taken from A to B via two different processes ACB and ADB.
    When the 'path ACB is used 60 J if heat flows into the system and 30 J of work is done by the system. If path ADB is used work done by the system is 10 J. The heat flows into the system in path ADB is:

    A) 80 J

    B) 20 J

    C) 100 J

    D) 40 J

    Correct Answer: D

    Solution :

    \[\Delta {{\text{Q}}_{\text{ACB}}}=\Delta {{\text{W}}_{\text{ACB}}}+\Delta {{\text{U}}_{\text{ACB}}}\]
    \[\Rightarrow \]   \[60J=30J+\Delta {{U}_{ABC}}\]
    \[\Rightarrow \]   \[\Delta {{\text{U}}_{\text{ABC}}}=30\,\text{J}\]
    \[\Rightarrow \]   \[\Delta {{U}_{ADB}}=\Delta {{U}_{ACB}}=\,30\,J\]
                \[\Delta {{Q}_{ACD}}=\Delta {{U}_{ACB}}+\Delta {{W}_{ADB}}\]
                \[=\,10\,\,J+30\,J=\,40\,J.\]


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