Question

Helium atom is two times heavier than a hydrogen molecule. At 298K, the average kinetic energy of a helium atom is:

• A. two times that of a hydrogen molecule
• B. same as that of a hydrogen molecule
• C. four times that of a hydrogen molecule
• D. half that of a hydrogen molecule

Answer 1

Answer: (B)

same as that of a hydrogen molecule

The expression for the average kinetic energy is $\left(ϵ\right)=\frac{3}{2}{k}_{B}T$.

Thus, average kinetic energy is independent of the molar mass.

Hence, at 298K, the average kinetic energy of a helium atom is same as that of a hydrogen molecule.

Hence, the correct answer is option $\text{B}$.