# What is the energy of the rotational motion of molecules contained in 1Kg of nitrogen at a temperature of $7^{\large\circ}C$

$\begin{array}{1 1}(A)\;4.2\times 10^4J\\(B)\;8.4\times 10^4J\\(C)\;12.6\times 10^4J\\(D)\;2.1\times 10^5J\end{array}$

Rotational degrees of freedom for a diatomic gas=2
Energy =$\large\frac{2}{2}$$nRT=8.4\times 10^4J$
Hence (B) is the correct answer.