The position of some metals in the electrochemical series in decreasing electropositive character is Mg > Al > Zn > Cu > Ag. In a chemical factory, a worker by accident used a copper rod to stir a solution of aluminium nitrate; he was scared that now there would be some reaction in the solution, so he hurriedly removed the rod from the solution and observed that
(A) the rod was coated with Al
(B) an alloy of Cu and Al was being formed.
(C) the solution turned blue in colour
(D) there was no reaction.
