Refer to figure `DeltaU_(1)` and `DeltaU_(2)` be the changes in internal energy in the system in process `A+B` and `DeltaW` be the net work done by the system in the process `A+B`,

Options

A. `DeltaQ-DeltaW=0`
B. `DeltaQ+DeltaW=0`
C. `DeltaU_(1)-DeltaU_(2)=0`
D. `DeltaU_(1)+DeltaU_(2)=0`

Answer

A, D

Explanation

As the system finally returns to its initial state, change in internal energy must be zero , i.e.,
`DeltaU=DeltaQ-DeltaW=0 or DeltaU=DeltaU_(1)+DeltaU_(2)=0`