The gas in the piston is being heated, and the piston has moved upward. The observation will be summarized in a row of the incomplete table below. A container with a piston inside it. An arrow above the piston points upward. Row Name Observation Variables 1 Boyle's law Volume increases when pressure decreases ? 2 Charles’s law ? ? 3 Gay-Lussac’s law ? Temperature, pressure 4 Combined gas law ? ? What are the variables for this piston? temperature only temperature and volume pressure and number of molecules volume and number of molecules.