The EAN of metal atoms in `[Fe(XO)_2(NO^+)_2]` and `Co_2 (CO)_8` respectively are :

Options

A. 34, 35
B. 34, 36
C. 36, 36
D. 36, 35

Explanation

To solve the problem of finding the Effective Atomic Number (EAN) of the metal atoms in the complexes \([Fe(XO)_2(NO^+)_2]\) and \(Co_2(CO)_8\), we will follow these steps:

### Step 1: Calculate the oxidation state of Iron in \([Fe(XO)_2(NO^+)_2]\)

1. Let the oxidation state of Iron be \(X\).
2. The oxidation state of \(XO\) (a neutral ligand) is 0.
3. The oxidation state of \(NO^+\) is +1.
4. The overall charge of the complex is neutral (0).

The equation can be set up as follows:

\[ X + 0 \cdot 2 + 1 \cdot 2 = 0 \]

This simplifies to:

\[ X + 2 = 0 \implies X = -2 \]

### Step 2: Calculate the EAN for Iron

The formula for EAN is:

\[ EAN = \text{Atomic Number} - \text{Oxidation State} + 2 \times \text{Coordination Number} + \text{Metal-Metal Bond Electrons} \]

1. The atomic number of Iron (Fe) is 26.
2. The oxidation state we calculated is +2.
3. The coordination number is the total number of ligands: 2 from \(XO\) and 2 from \(NO^+\), which gives us a total of 4.
4. There are no metal-metal bonds in this complex.

Substituting these values into the EAN formula:

\[ EAN = 26 - 2 + 2 \times 4 + 0 = 26 - 2 + 8 = 32 \]

### Step 3: Calculate the oxidation state of Cobalt in \(Co_2(CO)_8\)

1. Let the oxidation state of Cobalt be \(Y\).
2. The oxidation state of \(CO\) (a neutral ligand) is 0.
3. The overall charge of the complex is neutral (0).

The equation can be set up as follows:

\[ 2Y + 0 \cdot 8 = 0 \]

This simplifies to:

\[ 2Y = 0 \implies Y = 0 \]

### Step 4: Calculate the EAN for Cobalt

Using the EAN formula again:

1. The atomic number of Cobalt (Co) is 27.
2. The oxidation state we calculated is 0.
3. The coordination number is 8 (from 8 \(CO\) ligands).
4. There is a metal-metal bond between the two cobalt atoms, contributing 2 electrons.

Substituting these values into the EAN formula:

\[ EAN = 27 - 0 + 2 \times 8 + 2 = 27 + 16 + 2 = 45 \]

### Final Answer

The EAN of metal atoms in \([Fe(XO)_2(NO^+)_2]\) is **32**, and in \(Co_2(CO)_8\) is **45**.