Answer :
The reaction in which one element is replaced by another in a compound is known as displacement reaction. e.g.when Zinc reacts with copper solution, it gives zinc sulphate by displacing copper from copper sulphate solution. \( Zn{(s)}+CuSO_{4}{(aq)}\rightarrow ZnSO_{4}{(aq)}+Cu_{(s)} \) i. e. when Lead reacts with copper chloride it gives lead chloride by displacing copper from copper chloride. \( Pb{(s)}+CuCl_{2}{(aq)}\rightarrow PbCl_{2}{(aq)}+Cu_{(s)} \)