The complex(es) which is/are blue in colour:

Options

A. `Fe_(4)[Fe(CN)_(6)]_(3)`
B. `Zn_(2)[Fe(CN)_(6)]`
C. `Cu_(2)[Fe(CN)_(6)]`
D. `Fe_(3)[Fe(CN)_(6)]_(2)`

Answer

To determine which complexes are blue in color, we will analyze each of the given complexes one by one.

### Step-by-Step Solution:

1. **Identify the Complexes**: We have four complexes to analyze:
- A: Ferric Ferrocyanide
- B: Zinc Ferrocyanide
- C: Copper Ferrocyanide
- D: Ferroferric Cyanide

2. **Analyze Each Complex**:
- **Ferric Ferrocyanide (A)**: This complex is known as Peruvian blue and is recognized for its dark blue color.
- **Zinc Ferrocyanide (B)**: This complex is known to form a white precipitate, indicating it does not have a blue color.
- **Copper Ferrocyanide (C)**: This complex is known as chocolate brown precipitate, which suggests it has a reddish-brown color.
- **Ferroferric Cyanide (D)**: This complex is known as Turnbull's blue and is characterized by its blue color.

3. **Conclusion**: From the analysis:
- Ferric Ferrocyanide (A) is blue.
- Ferroferric Cyanide (D) is blue.
- Zinc Ferrocyanide (B) is white.
- Copper Ferrocyanide (C) is reddish-brown.

Thus, the complexes that are blue in color are **Ferric Ferrocyanide (A)** and **Ferroferric Cyanide (D)**.

### Final Answer:
The complexes which are blue in color are A (Ferric Ferrocyanide) and D (Ferroferric Cyanide).

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