ACS Chemistry Practice Exam 2025 – The All-in-One Guide to Exam Success!

According to Charles's Law, the relationship that remains constant is the volume and temperature of a gas when the pressure is held constant. This law states that the volume of a given mass of gas is directly proportional to its absolute temperature (measured in Kelvin) when pressure is constant.

Mathematically, it can be represented as V/T = k, where V is the volume, T is the temperature, and k is a constant. This means that if the temperature increases, the volume also increases, provided the pressure does not change, and vice versa.

In contrast, the other relationships mentioned do not hold true under the same conditions defined by Charles's Law. The volume and mass relationship does not account for temperature or pressure effects, and pressure and volume are related through Boyle's Law under constant temperature conditions, whereas pressure and temperature are interconnected in different gas laws when volume is kept constant. Therefore, the consistent relationship in Charles's Law is between volume and temperature.