Which statement best defines Charles/Gay-Lussac's Law?

The statement that the volume of gas is directly proportional to the change in absolute temperature at constant pressure accurately reflects Charles/Gay-Lussac's Law. This law illustrates the relationship between the volume of a gas and its temperature when the pressure remains constant. Specifically, as the temperature of a gas increases, its volume also increases, assuming the amount of gas (in moles) does not change and the pressure is held constant. This relationship can be expressed mathematically as V/T = k, where V is the volume, T is the absolute temperature, and k is a constant.

In contrast, the other statements do not correctly describe the relationship as outlined by Charles/Gay-Lussac's Law; they either misrepresent the nature of the relationship or incorrectly imply that no change occurs with temperature variations. Understanding this law is crucial when analyzing how gases behave under varying temperature conditions in practical scenarios, such as in dive physics where gas expansion can significantly impact buoyancy and other factors.