The degrees of freedom of the system is given by:- f = 3 N – K
Where, f = degrees of freedom
N = Number of Particles in the system.
K = Independent relation among the particles.
For a tri atomic gas; N = 3 and K = 3;
f = 3 X 3 – 3
f = 9-3= 6
Therefore, the degree of freedom of tri atomic gas is 6.