Which of the following compounds after mixing can produce blue colouration?
(I) `K_(4)[Fe(CN)_(6)] and FeCl_(3)` solution
(II) `NH_(4)OH and CuSO_(4)` solution
(III) Adding anhydrous `CuSO_(4)` to water
(IV) `NH_(4)OH+NiSO_(4)` solution
Choose the correct code:

Options

A. I,II,III
B. II,III
C. I,III
D. I,II,III,IV

Answer

To determine which of the given compounds can produce a blue coloration when mixed, we will analyze each option step by step.

### Step 1: Analyze the first option
**Compounds:** \( K_4[Fe(CN)_6] \) and \( FeCl_3 \)

**Reaction:** When potassium ferrocyanide (\( K_4[Fe(CN)_6] \)) is mixed with ferric chloride (\( FeCl_3 \)), it forms a complex known as Prussian blue, represented as \( KFe[Fe(CN)_6] \).

**Coloration:** This complex is known for its characteristic blue color.

**Conclusion:** This option produces blue coloration.

### Step 2: Analyze the second option
**Compounds:** \( NH_4OH \) and \( CuSO_4 \)

**Reaction:** When ammonium hydroxide (\( NH_4OH \)) reacts with copper sulfate (\( CuSO_4 \)), it forms copper hydroxide (\( Cu(OH)_2 \)).

**Coloration:** Copper hydroxide is a blue precipitate.

**Conclusion:** This option also produces blue coloration.

### Step 3: Analyze the third option
**Compounds:** Anhydrous \( CuSO_4 \) and water

**Reaction:** When anhydrous copper sulfate (\( CuSO_4 \)) is added to water, it hydrates to form copper sulfate pentahydrate (\( CuSO_4 \cdot 5H_2O \)).

**Coloration:** This hydrated form is blue in color.

**Conclusion:** This option produces blue coloration as well.

### Step 4: Analyze the fourth option
**Compounds:** \( NH_4OH \) and \( NiSO_4 \)

**Reaction:** When ammonium hydroxide (\( NH_4OH \)) is mixed with nickel sulfate (\( NiSO_4 \)), nickel hydroxide (\( Ni(OH)_2 \)) is formed.

**Coloration:** Nickel hydroxide is typically apple green in color, not blue.

**Conclusion:** This option does not produce blue coloration.

### Final Conclusion
Based on the analysis:
- Option I produces blue coloration.
- Option II produces blue coloration.
- Option III produces blue coloration.
- Option IV does not produce blue coloration.

Thus, the correct answer is options I, II, and III.

### Answer Code
The correct code is: **1, 2, 3**

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