The correct answer to the question is:
C. The principle of random molecular motion
Explanation:
1. The kinetic molecular theory describes the behavior of gases based on the motion of their particles.
2. According to this theory, gases consist of particles (molecules or atoms) that are in constant, random motion.
3. When a gas is at a constant temperature, its particles move randomly and collide with the walls of the container.
4. These collisions create pressure on the walls of the container.
5. When the volume of the container decreases, the same number of gas particles collide with a smaller area, leading to more frequent collisions and thus an increase in pressure.
6. Conversely, if the volume increases, the gas particles have more space to move around, resulting in fewer collisions per unit area and a decrease in pressure.
7. Therefore, the relationship between volume and pressure of a gas at constant temperature is explained by the principle of random molecular motion.
This principle helps us understand how changes in volume affect the pressure of a gas within a closed system at a constant temperature.