When to elements in different compounds trade places is what

A single replacement reaction, sometimes called a single displacement reaction, is a reaction in which one element is substituted for another element in a compound. The starting materials are always pure elements, such as a pure zinc metal or hydrogen gas, plus an aqueous compound.

Explanation:

The three types of chemical reactions are synthesis, decomposition, and replacement. Replacement – when one element replaces another element in a compound, or if two elements in different compounds trade places, the reaction is called a replacement.