The reaction representing the Mond process for metal refining is ____________.

Options

A. `Ni+4CO overset (Delta) to Ni(CO)_(4)`
B. `2K[Au(CN)_(2)]+Zn overset Delta to K_(2)[Zn(CN)_(4)]+2Au`
C. `Zr+2I_(2) overset (Delta) to ZrI_(4)`
D. `ZnO+C overset Delta to Zn+CO`

Answer

To determine the reaction representing the Mond process for metal refining, we need to understand the key aspects of this process. The Mond process is specifically used for refining nickel and involves the formation of nickel carbonyl.

### Step-by-Step Solution:

1. **Identify the Process**: The Mond process is a method for refining nickel. It involves the formation of nickel carbonyl, which is a volatile compound.

2. **Understand the Reaction**: The key reaction in the Mond process is:
\[ \text{Ni} + 4 \text{CO} \rightarrow \text{Ni(CO)}_4 \]
Here, nickel reacts with carbon monoxide to form nickel tetracarbonyl.

3. **Thermal Decomposition**: The nickel tetracarbonyl formed is then subjected to thermal decomposition:
\[ \text{Ni(CO)}_4 \rightarrow \text{Ni} + 4 \text{CO} \]
This step produces pure nickel and regenerates carbon monoxide, which can be recycled back into the process.

4. **Conclusion**: The overall reaction representing the Mond process can be summarized as:
\[ \text{Ni} + 4 \text{CO} \rightarrow \text{Ni(CO)}_4 \rightarrow \text{Ni} + 4 \text{CO} \]
Thus, the correct option that represents the Mond process is the first reaction provided in the options.

### Final Answer:
The reaction representing the Mond process for metal refining is:
\[ \text{Ni} + 4 \text{CO} \rightarrow \text{Ni(CO)}_4 \]