Question

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

• A. Same as that of a hydrogen molecule
• B. Half that of a hydrogen molecule
• C. Two times that of a hydrogen molecule
• D. Four times that of a hydrogen molecule.

Answer 1

The correct option is A Same as that of a hydrogen molecule

Average kinetic energy per molecule or atom $(=\frac{3}{2}KTwhereKisR/N_A)$ depends only on the temperature and does not depend upon the nature of the gas. Hence average kinetic energy of helium atom is same as that of a hydrogen molecule.