The cell reaction `Zn+Cu^(2+)rarrZn^(2+)+Cu`, is best represented by-

Options

A. `Cu//Cu^(2+)||Zn^(2+)//Zn`
B. `Zn//Zn^(2+)||Cu^(2+)Cu`
C. `Cu^(2+)//Cu||Zn//Zn^(2+)`
D. `Pt//Zn^(2+)||Pt//Cu^(2+)`

Answer

To represent the cell reaction \( \text{Zn} + \text{Cu}^{2+} \rightarrow \text{Zn}^{2+} + \text{Cu} \), we will follow a systematic approach to construct the electrochemical cell representation.

### Step-by-Step Solution:

1. **Identify the Anode and Cathode**:
- In the given reaction, zinc (Zn) is oxidized to zinc ions (\( \text{Zn}^{2+} \)), and copper ions (\( \text{Cu}^{2+} \)) are reduced to copper (Cu).
- Therefore, zinc is the anode (where oxidation occurs), and copper is the cathode (where reduction occurs).

2. **Write the Half-Reactions**:
- The oxidation half-reaction at the anode is:
\[ \text{Zn} \rightarrow \text{Zn}^{2+} + 2e^- \]
- The reduction half-reaction at the cathode is:
\[ \text{Cu}^{2+} + 2e^- \rightarrow \text{Cu} \]

3. **Construct the Cell Representation**:
- The standard notation for an electrochemical cell is:
\[ \text{Anode} \, | \, \text{Anode solution} \, || \, \text{Cathode solution} \, | \, \text{Cathode} \]
- For our reaction, the anode compartment will contain solid zinc and a solution of zinc ions (\( \text{Zn}^{2+} \)), while the cathode compartment will contain copper ions (\( \text{Cu}^{2+} \)) and solid copper.
- Thus, the cell representation becomes:
\[ \text{Zn} | \text{Zn}^{2+} || \text{Cu}^{2+} | \text{Cu} \]

4. **Include the Salt Bridge**:
- The salt bridge is used to maintain electrical neutrality by allowing the flow of ions. It is represented by the double vertical line (||) in the notation.

5. **Final Representation**:
- The complete cell representation is:
\[ \text{Zn} | \text{Zn}^{2+} || \text{Cu}^{2+} | \text{Cu} \]

6. **Select the Correct Option**:
- Based on the options provided, we need to identify which one matches our derived cell representation. The correct option will be the one that shows zinc as the anode and copper as the cathode with the appropriate ions.

### Conclusion:
The best representation of the cell reaction \( \text{Zn} + \text{Cu}^{2+} \rightarrow \text{Zn}^{2+} + \text{Cu} \) is:
\[ \text{Zn} | \text{Zn}^{2+} || \text{Cu}^{2+} | \text{Cu} \]