- Negligible forces of attraction hold gases.
- The molecules of gases are in continuous random straight-line motion.
- The molecules of gases collide with one another and the walls of the containing vessels.
- The collisions of gases are perfectly elastic. i.e. both kinetic energy and momentum are conserved.
- The average kinetic energy is proportional to the absolute temperature.
NB: Brownian motion, Osmosis, diffusion etc support Kinetic. theory of gases.