According to Boyle's Law, what happens to pressure when volume increases at constant temperature?

• A. Pressure increases as volume increases at constant temperature.
• B. Temperature decreases as volume increases at constant pressure.
• C. As volume increases, pressure decreases.
• D. Pressure remains constant as volume changes at constant temperature.

Answer: (C)

Boyle’s Law shows that for a fixed amount of gas at constant temperature, pressure and volume move in opposite directions. When you increase the volume, gas molecules have more space to move, so they collide with the container walls less often. Fewer collisions mean lower pressure. In other words, pressure is inversely related to volume for a constant amount of gas and temperature (P × V stays about the same).

So, as volume increases, pressure decreases. The other ideas don’t fit Boyle’s scenario: increasing volume while also claiming higher pressure contradicts the inverse relationship, and stating that temperature changes or that pressure stays constant doesn’t align with a fixed temperature and fixed amount of gas.