The correct answer is Exothermic reaction. Key Points - The formation of slaked lime (calcium hydroxide) Ca(OH)2 when water is added to lime (CaO) is exothermic. ∘CaO(s)+H2O(l)→Ca(OH)2(s) (Evolution of heat) - This reaction occurs when water is added to dry portland cement to make concrete, and the evolution of energy as heat is evident because the mixture becomes warm. - A chemical reaction in which heat energy is released is known as an exothermic reaction.
