Which of the following reactions are always exothermic? 1. Neutralization Il. Decomposition III. Combustion
Answer Details
Neutralization, decomposition, and combustion reactions can all be exothermic, but they don't have to be. An exothermic reaction is one that releases energy in the form of heat.
Neutralization reactions occur when an acid and a base react to form a salt and water. Some neutralization reactions can be exothermic because energy is released when the acid and base molecules come together to form a salt and water.
Decomposition reactions occur when a compound breaks down into its constituent elements. These reactions can be either endothermic or exothermic, depending on whether energy is absorbed or released during the reaction.
Combustion reactions involve a fuel and an oxidizer reacting to form water and carbon dioxide, and these reactions are almost always exothermic because they release energy in the form of heat and light.
Therefore, options (I and III only) are correct because neutralization and combustion reactions are usually exothermic. However, option (II) could be endothermic or exothermic, so it cannot be a correct answer. Option (I, II, and III) is also incorrect because option II could be endothermic.