Which of the following reactions can be classified as an endothermic process in aqueous solutions?

The dissolution of ammonium nitrate in water is classified as an endothermic process because it absorbs heat from the surrounding environment during the dissolution. When ammonium nitrate (NH4NO3) is added to water, the ionic compound separates into its constituent ions. This separation requires energy to overcome the attractive forces between the ions in the solid state. As a result, energy is drawn from the water, leading to a decrease in temperature in the solution. This characteristic heat absorption indicates that the reaction is endothermic.

In contrast, the dissolution of table salt in water is usually slightly exothermic, where heat is released as the ions separate and solvate in water. The mixing of water with hydrochloric acid is an exothermic reaction that releases heat due to the strong interactions between the water molecules and the acid. Lastly, the combustion of methane in water is a highly exothermic reaction, resulting in significant heat and light release as methane reacts with oxygen to form carbon dioxide and water. Thus, the process identified as the endothermic reaction is indeed the dissolution of ammonium nitrate in water.