Answer
d) Fe (s) + Cu²⁺ (aq) → Fe²⁺ (aq) + Cu (s)
Work Step by Step
Fe is higher than Cu on the activity series, so iron can displace or reduce copper from its salt. Thus a red coating of copper metal will form on the surface of iron metal causing the blue color of Cu²⁺ (aq) ions fades as the concentration of copper ions reduces.
