Question

how many elements are replaced in a displacement reaction?
two
one

Explanation:

In a displacement reaction, one element displaces another element from its compound. So, only one element is replaced. For example, in the reaction \( \text{Zn} + \text{CuSO}_4
ightarrow \text{ZnSO}_4 + \text{Cu} \), zinc (Zn) displaces copper (Cu) from copper sulfate, meaning only one element (Cu) is replaced by another (Zn).

Answer:

one