Question

Helium is two times heavier than H2. The average kinetic energy per molecule for helium at 300K is

• A. twice as H2
• B. same as H2
• C. half as H2
• D. one fourth of H2
• E.

Hint:

In the kinetic theory, the average kinetic energy per molecule is dependent only on temperature, not the molecular mass.

Answer 1

The Correct Option is B

According to the kinetic theory of gases, the average kinetic energy per molecule is proportional to the temperature and is independent of the type of gas: \[ KE = \frac{3}{2} k_B T \] Thus, at the same temperature, the average kinetic energy per molecule for helium is the same as that for hydrogen (H2).