Answer:
Answer is amount or moles of gas.
Step-by-step explanation:
Combined gas law is the law obtained by combination of the three gas laws for an ideal gas: Boyle's law,Charles's law and Gay-Lussac's law.
Boyle's law : pressure and volume of an ideal are inversely proportional. at constant temperature and moles.
Charles's law: Volume of a gas is directly proportional to temperature of gas, at constant pressure and moles.
Gay-Lussac's law: Pressure of a gas is directly proportional to temperature of gas, at constant volume and moles.
Combined gas law is PV/T = constant
So this is true for constant moles of gas or amount of gas.