Which gas law relates the volume and temperature of a gas at constant pressure?

Charles's Law specifically describes the relationship between the volume and temperature of a gas when the pressure remains constant. This law states that the volume of a gas is directly proportional to its absolute temperature (measured in Kelvin). Mathematically, this can be expressed as V/T = k, where V is volume, T is temperature, and k is a constant for a given sample of gas at constant pressure.

When the temperature of the gas increases, the kinetic energy of the gas particles also increases, causing them to move more vigorously and occupy a larger volume. Conversely, if the temperature decreases, the volume decreases as well. This characteristic of gases under constant pressure is what makes Charles's Law distinct and applicable in scenarios where temperature changes impact volume, such as in hot air balloons or in situations where gases are heated or cooled.

In contrast, the other laws mentioned—Boyle's Law (which relates volume and pressure), Avogadro’s Law (which relates volume and the amount of gas), and the Ideal Gas Law (which combines the relationships of pressure, volume, temperature, and moles of gas)—do not specifically address the relationship between volume and temperature at constant pressure. Thus, Charles's Law is the appropriate choice for this particular relationship.