Answer:
A - The volume of a gas varies directly with its temperature at constant pressure.
Step-by-step explanation:
Charles' Law states that, at constant pressure, the volume of a given amount of gas is directly proportional to its absolute temperature (measured in Kelvin). This means that as the temperature of a gas increases, its volume will increase proportionally, and vice versa.
This can be expressed mathematically as:
V ∝ T (at constant pressure)
or
V/T = constant (at constant pressure)
where V is the volume of the gas, T is its temperature in Kelvin, and the constant of proportionality is determined by the pressure and amount of gas.
So, option A accurately describes Charles' Law because it states that the volume of a gas varies directly with its temperature at constant pressure, which is consistent with the mathematical expression of the law. Options B, C, and D do not accurately describe Charles' Law, as they describe other laws that govern the behavior of gases under different conditions.