When an Metal is submerged in the solution of CuSO4 (Copper Sulphate) it takes place of Copper. This process is known as "single metal replacement reaction".
When Fe (iron) is added to CuSO4 (copper Sulphate) Fe(Iron) takes place of Cu (copper) and forms FeSO4 (Iron Sulphate).
Its chemical reaction is CuSO4 (copper Sulphate)+Fe (Iron) ------> FeSO4 (Iron Sulphate)+Cu (copper)
