Question

A helium atom is two times heavier than a hydrogen molecule. At 298 $K$, 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

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

Kinetic energy per mole or per molecule of a gas depends only on the temperature and not on the nature of the gas.

$KE=\frac{3}{2}RT$

So, average kinetic energy of a helium atom is the same as that of a hydrogen molecule.