Blue coloured compound are obtained when

Options

A. `Fe^(2+)` ion react with potassium ferriyanide
B. `Fe^(3+)` ion react with potassium ferrocyanide
C. `Fe^(3+)` ion react with potassium ferriyanide
D. `Fe^(2+)` ion react with potassium ferroyanide

Answer

To determine when blue-colored compounds are obtained, we will analyze the reactions involving iron ions and different types of cyanate compounds. Here’s a step-by-step solution:

### Step 1: Analyze the first option
- **Reaction**: Fe²⁺ + K₃[Fe(CN)₆] (potassium ferricyanate)
- **Result**: The reaction between Fe²⁺ ions and potassium ferricyanate produces a blue-colored compound.
- **Conclusion**: This option is correct.

### Step 2: Analyze the second option
- **Reaction**: Fe³⁺ + K₄[Fe(CN)₆] (potassium ferrocyanate)
- **Result**: The reaction between Fe³⁺ ions and potassium ferrocyanate initially produces a white compound, which can turn blue upon further reaction.
- **Conclusion**: This option is also correct.

### Step 3: Analyze the third option
- **Reaction**: Fe³⁺ + K₃[Fe(CN)₆] (potassium ferricyanate)
- **Result**: The reaction produces a brown-colored compound.
- **Conclusion**: This option is incorrect.

### Step 4: Analyze the fourth option
- **Reaction**: Fe²⁺ + K₄[Fe(CN)₆] (potassium ferrocyanate)
- **Result**: The reaction produces a white compound.
- **Conclusion**: This option is also incorrect.

### Final Conclusion
The blue-colored compounds are obtained from:
- **Option A**: Fe²⁺ reacting with potassium ferricyanate.
- **Option B**: Fe³⁺ reacting with potassium ferrocyanate.

### Summary of Correct Options
- **Correct Answers**: Option A and Option B.

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