Number of degrees of freedom (DOF) of a monatomic gas (e.g. helium) molecule:
- 1
- 2
- 3 (translational only)
- 5
Show answer and solution
Correct answer: C. 3 (translational only)
**Monatomic:** 3 translational DOF only.
No rotation contributes (a point mass has zero moment of inertia), no vibrations (single atom).
Internal energy per mole = (3/2)RT.