Assertion. When NO reacts with `FeSO_(4)`, a brown coloured complex is formed.
Reason. In the complex, the coordination number of Fe is + 6.

Options

A. If both assertion and reason are true, but reason is not the true explanation of the assertion
B. If both assertion and reason are true, but reason is not the true explanation of the assertion
C. If assertion is true, but reason is false
D. If both assertion and reason are false

Explanation

To solve the given assertion and reason question, we need to analyze both statements separately and determine their validity.

### Step 1: Analyze the Assertion
The assertion states that when NO (nitric oxide) reacts with FeSO₄ (iron(II) sulfate), a brown-colored complex is formed.

- **Explanation**: When nitric oxide reacts with iron(II) sulfate, it forms a complex known as nitrosyl iron complex, which is indeed brown in color. This is due to the formation of a coordination compound where NO acts as a ligand and coordinates to the iron center.

### Step 2: Analyze the Reason
The reason states that in the complex, the coordination number of Fe is +6.

- **Explanation**: The coordination number refers to the number of ligand atoms that are directly bonded to the central metal atom. In the case of the nitrosyl iron complex, the coordination number of iron (Fe) is typically +4, not +6. This is because NO is a monodentate ligand, meaning it can only bond through one site. Therefore, the assertion is true, but the reason is false.

### Step 3: Conclusion
- The assertion is true: A brown-colored complex is formed when NO reacts with FeSO₄.
- The reason is false: The coordination number of Fe in this complex is not +6.

### Final Answer
- The assertion is true, but the reason is false.

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