A closed system receives 200kJ of heat at constant volume. It then rejects 100kJ of heat while it has 50kJ of work done on it at constant pressure. If an adiabatic process can be found which will restore the system to its initial state, the work done by the system during this process is

Options

A. 100kJ
B. 50kJ
C. 150kJ
D. 200kJ

Answer

C

Explanation

`DeltaU_(n et)=0`
`:.` `DeltaU_1+DeltaU_2+DeltaU_3=0`
`:.` `Q_1+(Q_2-W_2)+DeltaU_3=0`
`(200kJ)+(-100+50)kJ+DeltaU_3=0`
`:.` `DeltaU_3=-150kJ`
In adiabatic process,
`W=-DeltaU`
`:.` `W_3=-DeltaU_3=150kJ`