The EAN of nickel in `Ni(CO)_4` is:

Options

A. (a) `38`
B. (b) `36`
C. (c) `28`
D. (d) `54`

Explanation

To find the Effective Atomic Number (EAN) of nickel in the complex `Ni(CO)4`, we can follow these steps:

### Step 1: Identify the Atomic Number of Nickel
The atomic number of nickel (Ni) is 28.

### Step 2: Determine the Oxidation State of Nickel
In the complex `Ni(CO)4`, carbon monoxide (CO) is a neutral ligand, meaning it does not contribute any charge. Since the overall charge of the complex is neutral (0), the oxidation state of nickel must also be 0.

### Step 3: Calculate the Number of Electrons Donated by the Ligands
Each CO ligand donates 2 electrons. Since there are 4 CO ligands in `Ni(CO)4`, the total number of electrons donated by the ligands is:
\[ 4 \text{ CO} \times 2 \text{ electrons/CO} = 8 \text{ electrons} \]

### Step 4: Apply the EAN Formula
The formula for calculating the Effective Atomic Number (EAN) is:
\[ \text{EAN} = \text{Atomic Number of Central Metal} - \text{Oxidation State} + \text{Electrons Donated by Ligands} \]
Substituting the values we have:
\[ \text{EAN} = 28 - 0 + 8 \]
\[ \text{EAN} = 36 \]

### Conclusion
The Effective Atomic Number (EAN) of nickel in `Ni(CO)4` is 36.

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