3. of the following element pairs listed, based on their valence electrons, which pair would form a covalent bond? A Silicon and Argon B Potassium and Bromine C Hydrogen and Sulfur D Hydrogen and Sodium

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.