Which scientific law states that the volume of a gas is directly proportional to its temperature at constant pressure?

The correct answer is Charles's Law, which articulates the relationship between the volume and temperature of a gas when pressure is held constant. According to this law, as the temperature of a gas increases, the volume also increases, provided the pressure remains the same. This is due to the kinetic molecular theory, which indicates that heating a gas increases the energy of its molecules, causing them to move more vigorously and occupy more space.

Charles's Law is commonly expressed mathematically as V1/T1 = V2/T2, where V represents volume and T represents temperature in Kelvin. It highlights not only the direct proportionality between volume and temperature but also the importance of absolute temperature in gas behavior.

In contrast, Boyle's Law describes the inverse relationship between pressure and volume at constant temperature, Avogadro's Law focuses on the volume of gas and the number of moles at constant temperature and pressure, and the Ideal Gas Law combines all these relationships into a single equation that accounts for pressure, volume, temperature, and the number of moles of gas.