• # question_answer   P-V plots for two gases during adiabatic process are shown in figure. Plots 1 and 2 should correspond, respectively, to   A) He and ${{O}_{2}}$ B) ${{O}_{2}}$ and He C) He and Ar D) ${{O}_{2}}$ and ${{N}_{2}}$

[b] Slope of adiabatic curve $\propto \gamma$$\propto \frac{1}{\text{Atomicity}\,\text{of}\,\text{the}\,\text{gas}}$. So, $\gamma$ is inversely proportional to atomicity of the gas.  [as $\gamma =1.66$ for monoatomic gas, $\gamma =1.4$ for diatomic gas, and $\gamma =1.33$ for triatomic non-linear gas.] From the graph it is clear that slope of curve 1 is less, so this should be adiabatic curve for diatomic gas (i.e., ${{O}_{2}}$). Similarly, slope of curve 2 is more, so it should be adiabatic curve for monoatomic gas (i.e. He).