When `K_(4)[Fe(CN)_(6)]` is treated with `FeCI_(3)` a blue colour is obtained It is due to the formation of .

Options

A. `Fe^(II)[Fe^(III)(CN)_(6)]^(Θ)`
B. `Fe^(III)[Fe^(II)(CN)_(6)]^(Θ)`
C. Both (a) and (b)
D. None of these

Explanation

To solve the question regarding the formation of a blue color when `K4[Fe(CN)6]` is treated with `FeCl3`, we can follow these steps:

### Step 1: Identify the Reactants
The reactants in this reaction are:
- `K4[Fe(CN)6]`, which is potassium hexacyanoferrate(II).
- `FeCl3`, which is iron(III) chloride.

### Step 2: Understand the Reaction
When `K4[Fe(CN)6]` is treated with `FeCl3`, a reaction occurs where the iron(III) ions from `FeCl3` interact with the cyanide ligands present in `K4[Fe(CN)6]`.

### Step 3: Formation of Complexes
The reaction leads to the formation of two types of complexes:
1. `Fe[Fe(CN)6]` - This complex contains iron in the +2 oxidation state.
2. `Fe(CN)6^3-` - This complex contains iron in the +3 oxidation state.

### Step 4: Color Change
The blue color observed in the solution is due to the formation of a complex known as Prussian blue, which is represented by the formula `Fe3[Fe(CN)6]2`. This complex exhibits a characteristic blue color.

### Step 5: Conclusion
Thus, the blue color obtained when `K4[Fe(CN)6]` is treated with `FeCl3` is due to the formation of the complex `Fe3[Fe(CN)6]2`, commonly known as Prussian blue.

### Final Answer
The blue color is due to the formation of `Fe3[Fe(CN)6]2` (Prussian blue).

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