A monoatomic gas expands at constant pressure on heating, The percentage of heat supplied that increases the internal energy of a gas and in the expansion is
 

Fraction of energy supplied for increment in internal energy 

$\begin{array}{l}=\frac{1}{\gamma }=\frac{3}{5}\left[\gamma =\frac{5}{3}\text{ For mono atomic gas }\right]\\ \therefore \text{ Percentage energy }=\frac{3\times 100}{5}=60\mathrm{\%}\\ \Rightarrow \text{ Fraction of energy supplied for external work done }=1-\frac{1}{\gamma }=\frac{\gamma -1}{\gamma }=\frac{2}{5}\\ \therefore \text{ Percentage energy }=\frac{2}{5}\times 100=40\mathrm{\%}\end{array}$