So, here , on adding zinc to CuSO4 solution, zinc displaces copper from copper sulfate & forms zinc sulfate solution. This is indicated by color change from blue to colorless. CuSO4 solution has a blue color while ZnSO4 solution is colorless. Zn(s) + CuSO4(aq) -> Cu(s) + ZnSO4 (aq).
