Answer: Pressure and volume.
- A Volume and temperature
- B Pressure and volume
- C Pressure and moles
- D Volume and moles
Correct answer: B. Pressure and volume
Explanation: Boyle Law states that at constant temperature, pressure and volume of a fixed amount of gas are inversely proportional.

Boyle's law: at constant temperature the pressure of a fixed mass of gas is inversely proportional to its volume (P ∝ 1/V), so the P–V plot is a hyperbola — halving the volume doubles the pressure. Image: Reginaprice2013, CC BY-SA 3.0, via Wikimedia Commons.
Concept context
Discover why gases expand to fill any container while liquids flow and solids hold their shape. Master the gas laws, the ideal gas equation, and the reasons real gases deviate from ideal behavior.