Answer: 5.
- A 3
- B 5
- C 6
- D 7
Correct answer: B. 5
Explanation: A diatomic molecule has 3 translational + 2 rotational degrees of freedom at moderate temperature, giving f = 5.
Not all gas molecules move at the same speed - the Maxwell-Boltzmann distribution shows the spread, with the most probable speed vp slightly less than the average vavg, which is slightly less than the root-mean-square speed vrms used in the pressure formula.
Concept context
Kinetic theory of gases connects molecular motion to pressure and temperature, explaining gas laws, specific heats, and molecular speeds.