Which process is considered endothermic?

An endothermic process is one that absorbs energy, typically in the form of heat, from its surroundings. Thermal decomposition is a prime example of an endothermic reaction, where a compound breaks down into simpler substances, requiring heat input to facilitate the reaction.

During thermal decomposition, the energy absorbed is used to break chemical bonds in the compound being decomposed. For instance, when calcium carbonate (CaCO₃) is heated, it decomposes into calcium oxide (CaO) and carbon dioxide (CO₂). This reaction requires heat, making it an endothermic process.

In contrast, neutralization involves an acid reacting with a base, releasing energy, which makes it an exothermic reaction. Catalysis refers to the acceleration of a reaction without being consumed, and it does not inherently absorb or release heat. Respiration is a metabolic process in which glucose is broken down with the release of energy, also classifying it as exothermic. Thus, thermal decomposition is the only process listed that fits the criteria of being endothermic.