Which assumption is part of the kinetic gas theory?

The assumption that molecules are in constant random motion is a fundamental aspect of the kinetic gas theory. This theory describes the behavior of gases by positing that gas molecules move freely and collide with each other and the walls of their container without significant loss of energy. This motion is random and continuous, leading to the various properties of gases, such as pressure and temperature, which are results of these molecular collisions.

Understanding that gas molecules are in constant motion helps explain why gases expand to fill their containers and why they are compressible. The rapid and random movement of these molecules also contributes to the diffusion of gases, which is the process of mixing and spreading out of gas particles in space. The kinetic gas theory is essential for explaining various gas behaviors under different temperature and pressure conditions.

In contrast to this correct assumption, the idea of gas molecules being at rest contradicts the very definition of gas behavior, as gases are characterized by their movement. The notion of significant intermolecular attraction or repulsion does not hold true in ideal gases as per the kinetic theory, which assumes negligible forces between molecules for large distances. Lastly, although the distance between gas molecules can be relatively large compared to their size, it is not considered negligible in the context of the kinetic theory,