Question

P-V plots for two gases during adiabatic process are shown in the figure. Plots 1 and 2 should respectively correspond to

• A. $He$ and $O_2$
• B. $O_2$ and $He$
• C. $He$ and $Ar$
• D. $O_2$ and $N_2$
  

Answer 1

The correct option is B $O_2$ and $He$

In adiabatic process, $P{V}^{\gamma }=constant$
For a monoatomic gas, $\gamma =C_p/C_v=1.67$
For a diatomic gas. $\gamma =1.4$
since, ${\gamma }_{diatomic}<{\gamma }_{monoatomic}$, with increase in volume, decrease in pressure would be more monoatomic gas.
Therefore, graph 1 is for diatomic and graph 2 is for monoatomic.