p-V plots for two gases during adiabatic process as shown in figure plots 1 and 2 should correspond 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

For adiabatic process, `PV^(gamma)` = constant
For monatomic gas, `gamma = C_p /C_V = 1.67`
For diatomic gas, `gamma = 1.4 `
Since `gamma _(" diatomic") lt gamma_("monatomic")` So with increase in volume, decrease in pressure will be more for monatomic gas.
`rArr` Graph 1 is for diatomic and Graph 2 is for monatomic.
Correct option is (C).