According to Boyle's law, what is considered as a constant?

Boyle's law states that the pressure of a gas is inversely proportional to its volume when temperature is held constant. Therefore, in the context of this law, temperature is the variable that must remain constant for Boyle's law to apply effectively.

When discussing the correct answer, it’s important to understand that while pressure and volume change relative to one another, temperature must not change in the experiment or scenario being examined. If the temperature were to vary, Boyle's law would no longer be applicable, as other gas laws would come into play, such as Charles's law, which relates to temperature and volume at constant pressure.

In setups governed by Boyle's law, pressure and volume will fluctuate as they are inversely related; when one increases, the other decreases, but this relationship holds true only under the condition that the temperature remains constant.