Thermodynamics Part 2

For polyatomic gas molecule has 3 rotational degrees of freedom, 3 translational degrees of freedom, and 2 vibrational modes.
So, number of vibrational degrees of freedom =2(2)=4
∴ Total number of degrees of freedom,
f=3+3+4=10
Here, ratio of molar specific heats is given as
β=‌

Cp

Cv

In terms of degrees of freedom, β=1+‌

2

f

Substituting the value of f in above equation, we get
β=1+‌

2

10

⇒β=1.2