A heat engine takes 4.0 moles of an ideal gas through the reversible cycle abca, on the pV diagram. The path bc is an isothermal process. The temperature at c is 420 K and the volumes at a and c are 0.02 m^3 and 0.23m^3, respectively. The molar heat capacity at constant volume, of the gas, is 39 J/mol*K. the heat absorbed by the gas, in kj is closest to:
-73
73
-60
60
zero