When applying Boyle's Law to a sample of gas, which quantity is held constant?

• A. Temperature
• B. Volume
• C. Number of moles
• D. Pressure

Answer: (A)

Verified step by step guidance

1. Recall that Boyle's Law describes the relationship between pressure and volume of a gas when other conditions are held constant.
2. Boyle's Law states that for a given amount of gas at constant temperature, the pressure of the gas is inversely proportional to its volume, which can be written as \(P \times V = \text{constant}\).
3. Identify the variables involved: Pressure (\(P\)) and Volume (\(V\)) change, while the temperature (\(T\)) and the number of moles (\(n\)) remain constant during the process described by Boyle's Law.
4. Understand that holding temperature constant means the gas's thermal energy does not change, allowing pressure and volume to adjust inversely without affecting the gas's internal energy.
5. Therefore, the quantity held constant when applying Boyle's Law is the temperature.