A reaction is exothermic when:_______.a. weak bonds break and strong bonds form. b. strong bonds break and weak bonds form. c. strong bonds break and strong bonds form. d. weak bonds break and weak bonds form.

An exothermic reaction is a chemical reaction that during the chemical reaction releases energy.
"Exo" means releases under the word Exothermic and "thermic" means heat.
Bonds are broken and replaced as chemical reactions occur, forming new materials.
When bonds are formed energy is released and for breaking of the bond, energy is needed.
Hence, when weak bonds are broken less amount of energy is needed and when a strong bond is formed a high amount of energy is released.