In which type of reaction does one element displace another in a compound?

In a single substitution reaction, an element in a compound is replaced by another element. This type of reaction typically occurs when a more reactive element displaces a less reactive one from its compound. For example, if zinc is added to a solution of copper sulfate, zinc will displace copper from the sulfate, resulting in the formation of zinc sulfate and elemental copper. This showcases how one element actively takes the place of another within a compound, which is the hallmark of a single substitution reaction.

In contrast, combinations of reactions involve two or more substances combining to form a single product, decomposition reactions involve a single compound breaking down into two or more elements or simpler compounds, and double substitution reactions involve the exchange of ions between two compounds, resulting in the formation of two new compounds. Each of these other types of reactions has a distinct mechanism that does not involve the direct displacement of one element by another within the same compound, which is why they do not apply in this context.