Logarithms of readings of pressure and volume for an ideal gas were plotted on a graph as shown in the given figure. By measuring the gradient, it can be shown that the gas may be

$\log \mathrm{P}=\mathrm{m} \log \mathrm{V}+{\mathrm{C}}_1$, where C₁ is positive, m is slope

$\mathrm{m}=\frac{2.38-2.10}{1.1-1.3}=-1.4$

$\log \mathrm{P}=-1.4\log \mathrm{V}+{\mathrm{C}}_1$

$\log {\mathrm{PV}}^{1.4}={\mathrm{C}}_1$

${\mathrm{PV}}^{1.4}=\mathrm{k}$

Thus, it represents an ideal diatomic gas undergoing adiabatic change.