Sol. We are given that V A = 10 l , V B = 1 l , V C = 10 l and p A = 1 atm.

A → B is an isothermal process, thus

pV = const. or p A V A = p B V B ,

hence

p B = p A = 10 atm.

(The curve AB of the two kinds of gas are the same).

B → C is an adiabatic process, thus

pV γ = const, or p B V B γ = p C V C γ , hence

p C = p B = 10 1– γ atm.

For the monatomic gas, we have

γ = 5/3, p C = 10 –2/3 = 0.215 atm.

For the diatomic gas, we have

γ = 7/5, p C = 10 –2/5 = 0.398 atm.

The two processes are shown in the figures (The cureve BC of monatomic gas is lower than that of the diatomic gas ).

In each case, as the curve AB for compression is higher than the curve BC for expansion, net work is done on the system. As p C (monatomic gas) < p C (diatomic gas) the work on the monatomic gas is greater than that on the diatomic gas.