Question

The quantity $\frac{2U}{fkT}$ represents (where $U=$ internal energy of gas)

• A. mass of the gas
• B. kinetic energy of the gas
• C. number of moles of the gas
• D. number of molecules in the gas

Answer 1

The correct option is D number of molecules in the gas

According to the law of Equipartition of energy to the molecule of a gas states that for each degree of freedom(f) for a molecule the associated energy is $\frac{1}{2}KT$

So, let $U$ be the total energy of all the molecules $n$ each having degree of freedom equal to $1.$

So, $U=nf\frac{1}{2}KT$

$\Rightarrow \frac{2U}{fKT}=n$

Hence, the answer is number of molecules in the gas.