question_answer

A gas can be taken from A to B via two different processes ACB and ADB. When path ACB is used 60 J of 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 Flow into the system in path ADB is: [JEE Main Online Paper (Held On 09-Jan-2019 Morning]

A) 40 J

B) 20 J

C) 100 J           

D) 80 J

Correct Answer: A

Solution :

  For Path ACB \[Q\text{ }=\text{ }60\text{ }J\] \[W\text{ }=\text{ }30\text{ }J\] \[\because \,\,\,\,Q\text{ }=\text{ }U\text{ }+\text{ }W\] \[\Rightarrow \,\,\,U\text{ }=\text{ }30\text{ }J\] Now, \[{{U}_{ACB}}\,\,=\,\,{{U}_{ADB}}\,\,=\,\,30\text{ }J\] For Path ADB:- \[U\,\,\,=\,\,30\text{ }J\] \[W=10\,J\] \[\Rightarrow \,\,\,Q=U+W=40\,J\] Option is correct.