Answer: B) exothermic
Explanation:
Endothermic: The chemical reactions in which reactants form products by absorption of energy are called as endothermic reactions.
Exothermic : The chemical reactions in which reactants form products along with release of energy are called as exothermic reactions. Thus if walls turn hot that means the energy has been released.
Reversible: The chemical reactions in which reactants form products and products can also be converted back to reactants are called as reversible reactions.
Irreversible: The chemical reactions in which reactants form products but products can not be converted back to reactants are called as irreversible reactions.
