Question

What is the degree of freedom of oxygen and argon?

Answer 1

The degrees of freedom are the number of values needed to describe the configuration of something. The configuration can refer to the position and orientation of an object. It can include angles of joints that are part of the object.

Oxygen molecule has 3 translational and 2 rotational degrees of freedom.

Assuming that the argon atoms are being treated as a classical system, then there are 3 degrees of freedom per atom. That assumes that we are neglecting electronic degrees of freedom, which is OK since one needs a fairly high temperature to thermally excite the electrons in argon.