Question

The number of Degree of freedom for a diatomic molecule is ________. (Assume molecules are rigid)
1. 2
2. 3
3. 5
4. 6

Answer 1

Correct Answer - Option 3 : 5

CONCEPT:

• Degree of Freedom (DOF): The number of independent ways by which a gas molecule can move, without any constraint imposed on it, is called the number of degrees of freedom.
  • For monoatomic molecule f = 3.
  • For diatomic molecule f = 5

CALCULATION:

• A diatomic molecule has a degree of freedom = 5, because
• It can move in translational motion in x y and z-direction.
• So the degree of freedom due to translational motion = 3
• Also due to rotational motion, degree of freedom = 2

So total degree of freedom = 3 + 2 = 5

• Hence the correct answer is option 3.