A gas, is heated at constant pressure. The fraction of heat supplied used for external work is:

$$\begin{gathered} We know that fraction of given energy that goes to increase the internal energy=\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$\gamma $}\right. \\ So, we can say the fraction of given energy that supplied for external work=1-\frac{1}{\gamma }. \end{gathered}$$