Intense blue precipitate of `Fe_(4)[Fe(CN)_(6)]_(3)` and potassium hydroxide solution when mixed gives:

Options

A. `K_(2)Fe[Fe(CN)_(6)]`-white precipitate
B. `Fe(OH)_(3)`-reddish -brown precipitate
C. `Fe(CN)_(3)`-reddish-brown precipitate
D. `K Fe[Fe(CN)_(6)]`-Turnbull's blue

Answer

To solve the question regarding the reaction of the intense blue precipitate of `Fe_(4)[Fe(CN)_(6)]_(3)` with potassium hydroxide (KOH), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
We have the intense blue precipitate of `Fe_(4)[Fe(CN)_(6)]_(3)` (known as Turnbull's Blue) and potassium hydroxide (KOH).

2. **Understand the Reaction**:
When `Fe_(4)[Fe(CN)_(6)]_(3)` is mixed with KOH, we need to consider the nature of the components. `Fe_(4)[Fe(CN)_(6)]_(3)` contains iron ions that can react with hydroxide ions from KOH.

3. **Write the Reaction**:
The reaction can be represented as:
\[ Fe_4[Fe(CN)_6]_3 + KOH \rightarrow Fe(OH)_3 + other products \]
Here, `Fe(OH)_3` is formed as a precipitate.

4. **Identify the Product**:
The product `Fe(OH)_3` is known to be reddish-brown in color. This is a key characteristic that helps us identify the outcome of the reaction.

5. **Conclusion**:
Therefore, when the intense blue precipitate of `Fe_(4)[Fe(CN)_(6)]_(3)` is mixed with potassium hydroxide, the resulting product is `Fe(OH)_3`, which is reddish-brown in color.

### Final Answer:
The mixture gives `Fe(OH)_3`, which is a reddish-brown precipitate.