In which sealed container would organisms be able to continuously cycle oxygen and carbon dioxide gases?
an aquarium with fish and plastic plants
a terrarium with a plant and a snail
an aquarium with rocks and a snail
a terrarium with tadpoles and a pool of water

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.