Assertion : The molecules of a monatomic gas has three degrees freedom.
Reason : The molecules of a diatomic gas has five degrees of freedom.

Options

A. If both assertion and Reason are true and the Reason is the correct explanation of the assertion.
B. If both assertion and Reason are true but the reason is not the correct explanation of the assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false.

Answer

B

Explanation

A monoatomic gas molecules (like the consists of a single atom. It can have translational motion in any direction in space. Thus, it has 3 translational degrees of freedom f=3 (all translational).
It can also rotate but due to its small moment of inertia rotational kinetic energy is neglected. the molecules of a diatomic gas (like `O_(2),CO_(2),H_(2)`) cannot only move bodily but also rotate about any one of the three coordinate axes. hence it can have only two rotational degrees of freedom. thus, a diatomic molecule has 5 degree of freedom 3 translational and 2 rotational.