What principle explains that the pressure exerted by a gas is inversely proportional to its volume, given constant temperature?

The principle that describes the relationship between pressure and volume of a gas, under conditions of constant temperature, is Boyle's Law. This law states that if the temperature remains constant, the pressure of a gas is inversely proportional to its volume. This means that as the volume of a gas increases, the pressure decreases, and vice versa, assuming the amount of gas and the temperature do not change.

For example, if you take a sealed container with a gas inside and decrease its volume by pushing down on the container, the molecules have less space to move around, causing them to collide with the walls more frequently, which increases the pressure. Conversely, if you allow the gas to expand by increasing its volume, the frequency of collisions with the walls decreases, resulting in a lower pressure.

The other principles mentioned do not apply to the same relationship. Bernoulli's Principle pertains to the behavior of fluid flow and pressure, Charles's Law deals with the relationship of volume and temperature at constant pressure, and Avogadro's Principle relates to the volume of gas in relation to the number of molecules at constant temperature and pressure.