The cell reaction `Hg_2Cl_2(s)+cu(s)to cu^(2+)(aq)+2Cl^-"(aq)+2Hg(l)`,best represented by :

Options

A. `cu(s)|cu^(2+)(aq)"||"Hg_2Cl_2(s)|Hg(l)`
B. `cu(s)|cu^(2+)(aq)"||"Hg(l)|HgCl_2(s)`
C. `cu(s)|cu^(2+)(aq)"||"Cl^-"(aq)|Hg_2Cl_2(s)|Hg(l)|Pt(s)`
D. `Hg_2Cl_2(s)|Cl^-"(aq)||Cu^(2+)(aq)|Cu(s)`

Answer

To solve the question regarding the cell reaction represented by `Hg2Cl2(s) + Cu(s) → Cu^(2+)(aq) + 2Cl^-(aq) + 2Hg(l)`, we need to follow these steps:

### Step 1: Identify the Oxidation and Reduction Reactions
In the given reaction, we can identify that:
- Copper (Cu) is being oxidized from 0 oxidation state to +2 oxidation state.
- Mercury (Hg) in `Hg2Cl2` is being reduced from +1 oxidation state to 0 oxidation state.

### Step 2: Write the Anodic Reaction
Since oxidation occurs at the anode, we can write the anodic reaction as:
\[ \text{Cu(s)} \rightarrow \text{Cu}^{2+}(aq) + 2e^- \]

### Step 3: Write the Cathodic Reaction
Reduction occurs at the cathode. The cathodic reaction involving the calomel electrode can be written as:
\[ \text{Hg}_2\text{Cl}_2(s) + 2e^- \rightarrow 2\text{Hg}(l) + 2\text{Cl}^-(aq) \]

### Step 4: Combine the Reactions
Now, we combine the anodic and cathodic reactions to represent the overall cell reaction:
- Anodic reaction: \( \text{Cu(s)} \rightarrow \text{Cu}^{2+}(aq) + 2e^- \)
- Cathodic reaction: \( \text{Hg}_2\text{Cl}_2(s) + 2e^- \rightarrow 2\text{Hg}(l) + 2\text{Cl}^-(aq) \)

### Step 5: Write the Cell Representation
The cell representation follows the format of:
\[ \text{Anode | Salt Bridge | Cathode} \]
Thus, we can write the cell representation as:
\[ \text{Cu(s)} | \text{Cu}^{2+}(aq) || \text{Hg}_2\text{Cl}_2(s) | \text{Hg}(l) + \text{Cl}^-(aq) \]

### Step 6: Include the Inert Electrode
In the case of a calomel electrode, we also need to include a reference to the KCl saturated solution, which is crucial for the reaction. Therefore, the complete representation becomes:
\[ \text{Cu(s)} | \text{Cu}^{2+}(aq) || \text{Hg}_2\text{Cl}_2(s) | \text{Hg}(l) + \text{Cl}^-(aq) | \text{KCl(saturated)} \]

### Final Answer
The best representation of the cell reaction is:
\[ \text{Cu(s)} | \text{Cu}^{2+}(aq) || \text{Hg}_2\text{Cl}_2(s) | \text{Hg}(l) + \text{Cl}^-(aq) | \text{KCl(saturated)} \]