Which statement describes Boyle's Law when the temperature and amount of gas are constant?

• A. PV product changes with temperature
• B. Pressure is directly proportional to Volume
• C. Volume is independent of Pressure
• D. The product of pressure and volume remains constant

Answer: (D)

At constant temperature and amount of gas, pressure and volume are tied together so that their product stays the same. This comes from PV = nRT; with n and T fixed, P×V must be a constant. So if you compress the gas to half its volume, the pressure doubles to keep the product the same. If you increase the volume, the pressure drops proportionally, keeping P×V constant. The other ideas don’t fit this situation: changing the product with temperature would violate the constant temperature condition; pressure directly proportional to volume contradicts the inverse relationship; and volume being independent of pressure ignores how P and V adjust together. Therefore, the description that the product of pressure and volume remains constant best reflects Boyle's Law here.