Consider the following experiments and answer the questions at the end of it
(A) When `Fe(CN)_(2)` solution is treated with `KCN` solution species formed no longer gives tests of `Fe^(2+)` and `CN^(Θ)`
(B) When `K_(2)SO_(4)` solution is treated with `A1_(2)(SO_(4))_(3)` solution species formed gives tests of `K^(o+),A1^(3+)` and `SO_(4)^(2-)`
`EAN` of iron formed in `(A)` is .

Options

A. 26
B. 24
C. 36
D. 38

Explanation

To solve the problem step by step, we will analyze the information given in the experiments and calculate the Effective Atomic Number (EAN) of iron in the coordination compound formed.

### Step 1: Identify the Coordination Compound
In experiment (A), `Fe(CN)2` is treated with `KCN`. The reaction leads to the formation of a coordination compound. The cyanide ion (CN^-) acts as a ligand and coordinates with the iron ion.

When `Fe(CN)2` reacts with `4 KCN`, it forms `K4[Fe(CN)6]`. This indicates that the iron is surrounded by six cyanide ligands.

### Step 2: Determine the Oxidation State of Iron
In the complex `K4[Fe(CN)6]`, the overall charge of the complex is neutral. Each cyanide ion (CN^-) has a charge of -1, and since there are six cyanide ions, they contribute a total charge of -6.

Let the oxidation state of iron be x. The equation for the charge balance is:
\[ x + 6(-1) = 0 \]
\[ x - 6 = 0 \]
\[ x = +6 \]

However, since we started with `Fe(CN)2`, we need to consider the oxidation state of iron in that compound. In `Fe(CN)2`, iron is in the +2 oxidation state.

### Step 3: Calculate the Effective Atomic Number (EAN)
The Effective Atomic Number (EAN) can be calculated using the formula:
\[ \text{EAN} = Z - n + 2m \]
where:
- Z = atomic number of the metal (iron in this case)
- n = oxidation state of the metal
- m = number of ligands (each donating 2 electrons)

1. **Atomic Number of Iron (Z)**: The atomic number of iron is 26.
2. **Oxidation State (n)**: The oxidation state of iron in the complex is +2.
3. **Number of Ligands (m)**: There are 6 cyanide ligands.

Now substituting the values into the EAN formula:
\[ \text{EAN} = 26 - 2 + 2(6) \]
\[ \text{EAN} = 26 - 2 + 12 \]
\[ \text{EAN} = 26 + 10 \]
\[ \text{EAN} = 36 \]

### Final Answer
The Effective Atomic Number (EAN) of iron formed in experiment (A) is **36**.

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