Mechanical for A/C Practice Test 2025 - Free HVAC Certification Practice Questions and Study Guide

Boyle's Law states that for a given mass of gas at a constant temperature, the pressure of the gas is inversely proportional to its volume. This means that if the volume of the gas increases, the pressure decreases, and vice versa, as long as the temperature remains unchanged.

In practical terms, this relationship can be visualized by imagining a sealed container with a gas inside. When the volume of that container is decreased by applying pressure (like pressing down on a piston), the molecules of the gas have less space to move around, resulting in a higher frequency of collisions with the walls of the container, which increases the pressure. Conversely, if the volume is expanded, the molecules have more space, leading to fewer collisions and a decrease in pressure.

The other options do not accurately describe this relationship. Directly proportional would suggest that pressure and volume increase or decrease together, which contradicts the principle of Boyle’s Law. Stating that there is no relationship or that it depends on temperature would also misrepresent the consistent inverse nature of pressure and volume at a constant temperature set by Boyle’s Law.