Question

Degree of freedom of unknown gas is $3$. The gas can be

• A. $H_2$
• B. $O_2$
• C. $C{O}_2$
• D. $He$

Answer 1

The correct option is D $He$

We know that, monoatomic gases have 3 degrees of freedom and diatomic and triatomic gases have more than 3 degrees of freedom.
Therefore, the given gas must be a monoatomic gas.
In the given options only $He$ is a monoatomic.
Therefore, correct option is $\left(d\right)$ Helium.