P-V diagram of an ideal gas is as shown in the given figure. Work done by the gas in the process ABCD is :

4 \(P_o V_o\) 2 \(P_o V_o\) 3 \(P_o V_o\) \(P_o V_o\)

3 \(P_o V_o\)

\(W_{AB} = - P_o V_o\) \(W_{BC} = 0 \text{ and } W_{CD} = 4 P_o V_o\) \(\Rightarrow W_{ABCD} = - P_o V_o + 0 + 4 P_o V_o = 3 P_o V_o\)