Question 17: Thermodynamics & KTG

Question

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

Accepted Answer

A monomatomic gas molecules like $\mathrm{He}$ consists of single atom. It can have translational motion in any direction in space. Thus, it has three translational degree 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 $\mathrm{O}_2, \mathrm{CO}_2, \mathrm{H}_2$) cannot only move body but also rotate about any one of the three co-ordinates. Hence it can have two rotational degree of freedom. Thus a diatomic molecule has 5 degree of freedom i.e. 3 translational and 2 rotational.

Answer

Both assertion and reason are true and reason is the correct explanation of assertion

Answer

Both assertion and reason are true but reason is not the correct explanation of assertion

Answer

Assertion is true but reason is false

Answer

Both assertion and reason are false.

Thermodynamics & KTG

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

Choose the correct answer: