Which of the following chemical equation represents a displacement reaction

A displacement reaction occurs when a more reactive element displaces a less reactive element from its compound.

Let's analyze each equation:

• A. $2\text{Al}(\text{s}) + 3\text{I}_2(\text{s}) \rightarrow 2\text{AlI}_3(\text{s})$ This is a combination reaction, where two elements combine to form a single compound.

• B. $\text{CuCO}_3(\text{s}) \rightarrow \text{CuO}(\text{s}) + \text{CO}_2(\text{g})$ This is a decomposition reaction, where a single compound breaks down into two simpler substances.

• C. $2\text{NaCl}(\text{l}) \rightarrow 2\text{Na}(\text{l}) + \text{Cl}_2(\text{g})$ This is a decomposition reaction, where a compound breaks down into its constituent elements.

• D. $\text{Fe}(\text{s}) + \text{CuSO}_4(\text{aq}) \rightarrow \text{FeSO}_4(\text{aq}) + \text{Cu}(\text{s})$ In this reaction, elemental iron ($\text{Fe}$) displaces copper ($\text{Cu}$) from copper(II) sulfate ($\text{CuSO}_4$) to form iron(II) sulfate ($\text{FeSO}_4$) and elemental copper ($\text{Cu}$). This is a single displacement reaction because iron is more reactive than copper.

The final answer is $\boxed{\text{D}}$.