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The number of translational degrees of freedom for a diatomic gas is

Asked in NEET 1993 · Degrees of freedom and equipartition

Answer: (2) 3

Step-by-step solution

Translational degrees of freedom count the independent directions in which a molecule's centre of mass can move.

Space has three such directions, whatever the shape of the molecule.

A rigid diatomic molecule adds two rotational modes, about the two axes perpendicular to the bond, giving five in all.

But those extra two are rotational, not translational.

So the number of translational degrees of freedom is 3.

Why the other options are wrong

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