Q.

An ideal gas exists in a state with pressure P0, volume V0. It is isothermally expanded to 4 times of its initial volume (V0), then isobarically compressed to its original volume. Finally the system is heated isochorically to bring it to its initial state. The amount of heat exchanged in this process is:          [2025]

1 P0V0(2 ln 20.75)  
2 P0V0(ln 20.75)  
3 P0V0(ln 20.25)  
4 P0V0(2 ln 20.25)  

Ans.

(1)

Q=U+W

For cyclic process Q = W

W=W1+W2+W3

      =P0V0 ln 4V0V0+P04(V04V0)+0

      =P0V0 ln 434P0V0

      =P0V0(2 ln 20.75)