Which of the following best describes Charles's Law in relation to volume and pressure of a gas at constant pressure?

• A. At constant pressure, the volume of a gas is directly proportional to its temperature.
• B. At constant pressure, the volume of a gas is inversely proportional to its pressure.
• C. At constant temperature, the volume of a gas is inversely proportional to its pressure.
• D. At constant volume, the pressure of a gas is directly proportional to its temperature.

Answer: (A)

Verified step by step guidance

1. Understand that Charles's Law describes the relationship between the volume and temperature of a gas when the pressure is held constant.
2. Recall that Charles's Law states that the volume of a gas is directly proportional to its absolute temperature (in Kelvin) at constant pressure.
3. Express Charles's Law mathematically as \(V \propto T\) or \(\frac{V_1}{T_1} = \frac{V_2}{T_2}\), where \(V\) is volume and \(T\) is temperature.
4. Recognize that this means if temperature increases, volume increases proportionally, and if temperature decreases, volume decreases proportionally, as long as pressure remains constant.
5. Compare the given options to this understanding and identify the statement that matches Charles's Law: 'At constant pressure, the volume of a gas is directly proportional to its temperature.'