Question

P-V plots for two gases adibatic processes are shown in the figure. Plots 1 and 2 should correspond respectively

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

Answer 1

Answer: (B)

$O_2$ and He

For adiabatic processes, $P{V}^{\gamma }=$constant
When Pressure decrease, Volume has to increase to maintain the above relation.
Even as Volume increases, the increase is volume would be higher when the exponent $\gamma$ has a lower value than when the value of $\gamma$ is higher.
So, when $\gamma$ is higher, for monoatomic it is 1.6, the value of V is smaller compared to the value of V for which $\gamma$ is lower, diatomic it is 1.4
Hence, Plot 1 corresponds to lower $\gamma$-diatomic-$O_2$
Plot 2 corresponds to higher $\gamma$-monoatomic-$He$