Question

Which of the following gas molecules have equal total kinetic energy and translational kinetic energy?

• A. $O _{2}$
• B. $He$
• C. $CH _{4}$
• D. $N _{2}$

Answer 1

Answer: (B)

$He$

Answer 2

The total kinetic energy of a molecule is the sum of its translational, vibrational and rotational kinetic energies. The monoatomic molecules do not possess vibrational and rotational kinetic energies. Hence noble gases (like $He, Ar$ etc) fulfill the criteria.