The Combined Gas Law relates which variables for a fixed amount of gas?

• A. Pressure and Volume
• B. Temperature and Amount
• C. Pressure, Volume, and Temperature
• D. Volume and Temperature

Answer: (C)

Pressure, volume, and temperature are all interconnected for a fixed amount of gas. From PV = nRT, when the amount n is constant, the ratio PV/T stays the same as conditions change. The Combined Gas Law captures this by linking all three variables in the form P1V1/T1 = P2V2/T2. This shows how changing one quantity affects the others, with temperature kept in Kelvin for an accurate absolute scale. It brings together the behavior described by Boyle’s, Charles’s, and Amontons’ laws into one relation. For example, at constant volume, increasing temperature raises pressure proportionally; at constant temperature, decreasing volume raises pressure; and so on, all governed by the same P, V, and T connections.