question_answer

A gas can be taken from A to B via two different processes ACB and ADB.

[JEE Main 09-Jan-2019 Morning]

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:

A)        40 J    

B)  20 J

C)  100 J              

D)       80 J

Correct Answer: A

Solution :

 

[a]

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 [a] is correct.