A sample of gas occupies 3.25 L at 121 °C. If the volume of the gas decreases to 1.25 L, what other change will occur if the pressure remains
constant at 710.0 mm Hg? *

Please hurry what is the answer to this?

Which statement is true about a catalyst? a: a catalyst decreases the rate of the reaction. b. a catalyst is consumed during a chemical reaction. c. a catalyst lowers the activation energy of a reaction. d. a catalyst increases the reactant concentration during a reaction.