In an adiabatic expansion of an ideal gas the product of pressure and volume

A certain amount of heat energy is supplied to a monoatomic ideal gas which expands at constant pressure. What fraction of the heat energy is converted into work?

A thermodynamic system undergoes a cyclic process $$A B C$$ as shown in the diagram. The work done by the system per cycle is

One mole of $$\mathrm{O}_2$$ gas is heated at constant pressure starting at $$27^{\circ} \mathrm{C}$$. How much energy must be added to the gas as to double its volume?