Help see whats the differences and what they have alike

Achange in the number of neutrons in an atom will change an blank . when the number of protons changes in an atom, a new element will form.

How does a catalyst increase the speed of a reaction? a. the catalyst eliminates the activated complex stage, allowing products to form immediately. b. the catalyst lowers the energy level of the reactants, making it easier for them to react. c. the catalyst makes it easier for the activated complex to form, lowering the activation energy. d. the catalyst raises the energy level of the products, making the reaction finish sooner. reset next

The same side of the moon always faces earth because the