Assertion: Nickel is purified by reaction it with `CO`.
Reason: Impurities present in nickel form volatile compounds.

Options

A. If both (A) and ( R) are correct and ( R) is the correct explanation of (A).
B. If both (A) and ( R) are correct, but ( R) is not the correct explanation of (A).
C. If (A) is correct, but ( R) is incorrect.
D. If (A) is incorrect, but ( R) is correct.

Explanation

**Step-by-Step Text Solution:**

1. **Understanding the Assertion:**
The assertion states that nickel is purified by reacting it with carbon monoxide (CO). This is indeed true. Nickel can be purified through a process that involves its reaction with CO.

2. **Understanding the Reason:**
The reason given is that the impurities present in nickel form volatile compounds. This is also true. During the purification process, the impurities do not react with carbon monoxide in the same way that nickel does, and as a result, they remain in the solid state while nickel forms a volatile compound.

3. **The Process of Purification:**
The purification of nickel is commonly done using the Mond process. In this process, nickel ore is heated in the presence of carbon monoxide. The nickel reacts with CO to form nickel tetracarbonyl (Ni(CO)₄), which is a volatile compound.

4. **Separation of Impurities:**
As the nickel forms this volatile compound, the impurities (gangue) present in the ore do not react with CO and remain as solid residues. This allows for the separation of pure nickel from the impurities.

5. **Conclusion:**
Therefore, both the assertion and the reason are correct. The assertion is that nickel is purified by reacting with CO, and the reason explains that the impurities form non-volatile residues, which supports the assertion.

**Final Answer:**
Both the assertion and reason are correct, and the reason is the correct explanation of the assertion.

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