With which of the following metals, `CO` forms a volatile carbonyl complex?

Options

A. `Na`
B. `Sn`
C. `Ni`
D. `Hg`

Answer

To determine which metal forms a volatile carbonyl complex with carbon monoxide (CO), we can follow these steps:

### Step 1: Understand Carbonyl Complexes
Carbonyl complexes are compounds formed when carbon monoxide (CO) binds to a metal. The nature of the metal affects the stability and volatility of the resulting complex.

### Step 2: Identify the Metals in the Options
The metals given in the options are:
- Na (Sodium)
- Sn (Tin)
- Hg (Mercury)
- Ni (Nickel)

### Step 3: Analyze Each Metal's Interaction with CO
1. **Sodium (Na)**: Sodium does not form stable carbonyl complexes with CO.
2. **Tin (Sn)**: Tin can form some carbonyls, but they are not typically volatile.
3. **Mercury (Hg)**: Mercury forms carbonyl complexes, but they are not known to be volatile.
4. **Nickel (Ni)**: Nickel forms a well-known volatile carbonyl complex, nickel tetracarbonyl (Ni(CO)₄).

### Step 4: Conclusion
Among the given metals, only nickel (Ni) forms a volatile carbonyl complex, specifically Ni(CO)₄, which is known to be a gas at room temperature.

### Final Answer
The metal with which CO forms a volatile carbonyl complex is **Nickel (Ni)**.

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