Activation energy is necessary for a chemical reaction to occur because .

a. breaking bonds requires energy
b. some reactions happen at cold temperatures
c. alll reactions are endothermic
d. forming bonds requires energy

A chemical that keeps food spoiling is an example of .

a. a catalyst
b. an enzyme
c. a reactant
d. an inhibitor

Presence of a catalyst .

a. stops a reaction
b. raises the activation energy needed
c. slows down a reaction
d. reduces the activation energy needed