A: `[FeCN)_(6)]^(4-)` follows EAN rule.
R: Number of electrons in Fe in this complexionis 36

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. ) If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statements, then mark (4)

Answer

To solve the question, we need to analyze the assertion and reason provided regarding the complex ion \([Fe(CN)_6]^{4-}\) and its effective atomic number (EAN).

### Step-by-Step Solution:

1. **Identify the Central Metal and Its Atomic Number**:
- The central metal in the complex is Iron (Fe).
- The atomic number of Iron (Fe) is 26.

2. **Determine the Oxidation State of Iron**:
- The complex is \([Fe(CN)_6]^{4-}\).
- The cyanide ion (\(CN^-\)) has an oxidation state of -1.
- Since there are 6 cyanide ions, the total contribution from the ligands is \(6 \times (-1) = -6\).
- Let the oxidation state of Iron be \(x\). The overall charge of the complex is -4.
- Therefore, we can set up the equation:
\[ x + (-6) = -4 \]
- Solving for \(x\):
\[ x - 6 = -4 \implies x = +2 \]
- Thus, the oxidation state of Iron in this complex is +2.

3. **Calculate the Number of Electrons Donated by the Ligands**:
- Each cyanide ion donates 2 electrons (as it is a bidentate ligand).
- With 6 cyanide ions, the total number of electrons donated is:
\[ 6 \times 2 = 12 \text{ electrons} \]

4. **Apply the EAN Formula**:
- The formula for Effective Atomic Number (EAN) is:
\[ \text{EAN} = \text{Atomic Number of Metal} - \text{Oxidation State} + \text{Electrons from Ligands} \]
- Plugging in the values:
\[ \text{EAN} = 26 - 2 + 12 \]
- Simplifying this gives:
\[ \text{EAN} = 26 - 2 + 12 = 36 \]

5. **Conclusion**:
- The effective atomic number of Iron in the complex \([Fe(CN)_6]^{4-}\) is 36, which is equal to the atomic number of the noble gas Krypton (Kr).
- Therefore, the assertion that the complex follows the EAN rule is true, and the reason that the number of electrons in Iron in this complex is 36 is also true.

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

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