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

Options

A. `He and O_(2)`
B. `O_(2) and He`
C. `He and Ar`
D. `O_(2) and N_(2)`

Answer

B

Explanation

In an adiabatic process, slope of `P-V` graph
`=(dP)/(dV)= -gammaP/V`
i.e., slope prop gamma (with negative sign)
In (figure) `("slope")_(2) gt ("slope")_(1) :. gamma_(2) gt gamma_(1)`
`:.` Plot 1 corresponds to `O_(2)(gamma=1.4)` and Plot 2 corresponds to `He(gamma-1.67)`. Choice (b) is correct.