According to the Ideal Gas Equation, with temperature and amount of gas held constant, what is the effect of increasing pressure on the gas volume?

• A. As the pressure increases, the volume decreases.
• B. As the pressure increases, the volume increases.
• C. The volume equalizes despite pressure changes.
• D. The volume and pressure are unrelated

Answer: (A)

When temperature and amount of gas are held constant, the product P × V remains constant (PV = nRT with n and T fixed). That means pressure and volume are inversely related. If you raise the pressure, the volume must shrink to keep the product the same.

So increasing pressure leads to a smaller volume. The other ideas conflict with this inverse relationship: increasing pressure should not cause the volume to increase, nor should the volume stay the same or be unrelated to pressure when temperature and amount are fixed.