Answer: 3.
- A 2
- B 3
- C 5
- D 6
Correct answer: B. 3
Explanation: A monatomic gas molecule (like helium) has only 3 translational degrees of freedom and no rotational or vibrational modes.
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.