When one molecule of calcium oxide (CaO) reacts with one molecule of carbon dioxide (CO₂), they combine to form calcium carbonate (CaCO₃). This is a typical reaction that occurs when calcium oxide, a basic oxide, reacts with carbon dioxide, leading to the formation of a carbonate.
The balanced chemical equation for this reaction is:
\[ \text{CaO} + \text{CO}_2 \rightarrow \text{CaCO}_3 \]
Thus, the chemical formula that identifies the product of this reaction is CaCO₃.