The most negative electron affinity is most likely associated with which type of atoms?

Can someone me with questions 12 and 13 plz.

The continuous release of nuclear energy caused when one fission reaction triggered more nuclear reactions is a

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.