Charles's Law states that the volume of a gas is directly proportional to what factor at constant pressure?

Charles's Law defines the relationship between the volume and temperature of a gas at constant pressure. Specifically, it states that the volume of a gas increases as its temperature increases, provided that pressure remains constant. This relationship can be formulated mathematically as V ∝ T, where V represents volume and T represents the absolute temperature measured in kelvins.

The principle behind this law is rooted in the kinetic molecular theory, which explains that as the temperature of a gas increases, the kinetic energy of its molecules also increases. This heightened energy causes the molecules to move more vigorously and collide with the walls of the container with greater force, resulting in an increase in volume.

In this context, while the pressure, mass, and number of molecules in the system have their significance, they do not directly relate to the volume variation with temperature as outlined by Charles's Law. Therefore, the correct answer is that the volume of a gas is directly proportional to the kelvin temperature of the gas when pressure is kept constant.