KMT is an abbreviation of the kinetic molecular theory of gases, which is a model that describes the behaviour of gaseous substances. It does so by using the microscopic components of gaseous substances (such as atoms and molecules) to explain the macroscopic behaviour and properties of gaseous substances (such as its absolute temperature and pressure). The assumptions of the kinetic molecular theory of gases are:
a) All gaseous substances are made up of numerous gaseous particles that do not have any defined volume but do have a definite mass. In other words, the volume occupied by a gaseous particle is negligible when compared to the average distance between two particles.
b) The particles of a gaseous substance do not experience any intermolecular forces (repulsive or attractive). Therefore, the total energy of the gaseous particle is equal to its kinetic energy.
c) The particles that constitute gases are always in a state of constant motion (the direction of the motion is always random).
d) The collisions that occur between two or more gaseous particles are always perfectly elastic (no net loss/gain in kinetic energy can be observed).
e) The average value of the kinetic energy of a gaseous particle is exactly the same for all gases (when the temperature is kept constant). The average kinetic energy is directly proportional to the absolute temperature of the gas.