P - V plots for two gases, undergoing adiabatic processes are as shown in the figure.

Plots 1 and 2 should correspond respectively to

Options

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

Answer

C

Explanation

For an adiabatic process `PV^(gamma)` = constant
`thereforeP*rV^(gamma-1)dV+V^(gamma)dP=0`
`thereforegammaPdV=-VdPor(dP)/(dV)=-(gammaP)/V`
`therefore` Slope of the graph `prop gamma`
In the given graph `("slope")_(2)gt("slope")_(1)orgamma_(2)gtgamma_(1)`
`therefore` 2 corresponds to monoatomic Helium `[gamma=1.67]`
and 1 corresponds to diatomic `O_(2)" "[gamma=1.4]`