Final answer:
The reaction CaCO3(s) → CaO(s) + CO2(g) is identified as a decomposition reaction, where calcium carbonate decomposes into calcium oxide and carbon dioxide when heated.
Step-by-step explanation:
The reaction CaCO₃ (s) → CaO (s) + CO₂ (g) represents a decomposition reaction, where a single compound, calcium carbonate (CaCO₃), breaks down into two products calcium oxide (CaO) and carbon dioxide gas (CO₂). This type of reaction often requires heating and leads to the formation of simpler substances from a single reactant.
Decomposition reactions are the opposite of combination reactions. In the context of this question, CaCO₃ decomposes into CaO and CO₂ upon heating and is a classic example of this type of chemical reaction in chemistry. In contrast, a combination reaction would produce a single compound from multiple reactants.