Answer: moving molecules.
- A moving molecules
- B fixed atoms
- C charged plates
- D liquid droplets
Correct answer: A. moving molecules
Explanation: A gas is treated as many small molecules in constant random motion.
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.