Question

$P-V$ plots for two gases during adiabatic processes are shown in Fig. 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 $N_2$

Answer 1

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

For adiabatic process, $P{V}^{\gamma }=constant$
For monatomic gas, $\gamma =\frac{C_p}{C_v}=1.67$
For diatomic gas, $\gamma =1.4$
Since ${\gamma }_{diatomic}<{\gamma }_{monatomic}$, so with increase in volume, decrease in pressure will be more for monatomic gas.
$\Rightarrow Graph1$ is for diatomic and Graph $2$ is for monatomic.
Correct option is (b).