Which statement is NOT a postulate of the Kinetic Molecular Theory of gases?

Which statement is NOT a postulate of the Kinetic Molecular Theory of gases?

• A. The collisions between molecules are elastic.
• B. The gas molecules are in constant, random motion.
• C. At lower temperatures, molecules have higher kinetic energies.
• D. The volumes of the molecules are negligible compared with the volume of the container.

Answer: (C)

The main idea here is how the kinetic molecular theory describes gas behavior through basic statements about motion, energy, collisions, and volume. The statement that does not fit is the one that says lowering temperature gives higher kinetic energy. In the kinetic molecular view, temperature is a measure of the average kinetic energy of the gas molecules, and as temperature decreases, the average kinetic energy decreases as well. So lower temperatures correspond to less molecular motion, not more. The other statements line up with the theory: gas molecules move constantly and randomly, reflecting their random, continual motion; collisions between molecules and with the container are elastic, meaning no net loss of kinetic energy in those collisions; and the volume occupied by the gas molecules themselves is negligible compared with the container’s volume, allowing most space to be empty for motion.

The main idea here is how the kinetic molecular theory describes gas behavior through basic statements about motion, energy, collisions, and volume. The statement that does not fit is the one that says lowering temperature gives higher kinetic energy. In the kinetic molecular view, temperature is a measure of the average kinetic energy of the gas molecules, and as temperature decreases, the average kinetic energy decreases as well. So lower temperatures correspond to less molecular motion, not more.

The other statements line up with the theory: gas molecules move constantly and randomly, reflecting their random, continual motion; collisions between molecules and with the container are elastic, meaning no net loss of kinetic energy in those collisions; and the volume occupied by the gas molecules themselves is negligible compared with the container’s volume, allowing most space to be empty for motion.