The cell reaction \(Zn + Cu^{2+} \rightarrow Zn^{2+} + Cu\) is best represented by

Zn | Zn²⁺ || Cu²⁺ | Cu

The correct answer is option 2. Zn | Zn²⁺ || Cu²⁺ | Cu

The cell reaction \(Zn + Cu^{2+} \rightarrow Zn^{2+} + Cu\) is best represented by (2) Zn | Zn²⁺ || Cu²⁺ | Cu.

The cell representation shows the two half-cells, the anode and the cathode, separated by a salt bridge. The anode is where oxidation occurs, and the cathode is where reduction occurs. In this reaction, zinc is oxidized to Zn²⁺ at the anode, and Cu²⁺ is reduced to Cu at the cathode.

The salt bridge is a device that allows ions to flow between the two half-cells, but it prevents the solutions from mixing. This is important because the solutions in the two half-cells must be electrically isolated from each other, but they must also be able to exchange ions.

The correct order of the metals in the cell representation is also important. The metal that is oxidized is always written on the left side of the cell representation, and the metal that is reduced is always written on the right side.

Therefore, the correct cell representation is Zn | Zn²⁺ || Cu²⁺ | Cu.