The typical speed of a reaction releases gas every twenty seconds for two minutes. the chart lists four substances that were added to the reaction at different times. substances w and y are catalysts, and substances x and z are inhibitors. substance w is an inhibitor, and substances x, y, and z are catalysts. substances w and z are inhibitors, and substances x and y are catalysts. substance x is a catalyst, and substances w, y, and z are inhibitors.