Q.State the basic assumptions of the kinetic theory of gases as applied to an ideal gas.

Kinetic theory rests on a small set of idealised assumptions about an ideal gas's molecules:

1. A gas consists of a very large number of identical molecules in ceaseless, random motion, moving in every direction with a range of speeds.
2. The size of a molecule is negligible compared to the average distance between molecules -- each molecule is treated as a point mass.
3. Molecules exert no force on one another except during a collision; between collisions they move in straight lines at constant velocity.
4. Collisions (molecule-molecule or molecule-wall) are perfectly elastic and of negligible duration.
5. Molecules obey Newton's laws of motion at every instant.
6. Gravity is neglected for an individual molecule's motion between collisions.

List the standard set of kinetic-theory assumptions in order: molecular size, random motion, elastic collisions, Newton's laws, negligible gravity.

• Forgetting that collisions are assumed PERFECTLY elastic (no kinetic energy lost overall), not just approximately so.
• Omitting that molecular SIZE is assumed negligible compared to the separation between molecules -- this is what lets a molecule be treated as a point mass.