The aqueous solution of potassium cyanide is mixed with aqueous solution of `F_e(CN)_2` . The resulting solution will give test for

Options

A. `K^+ and CN^(-)` ions
B. `K^(+) , Fe ^(2+) and CN^(-)` ions
C. `K^(+) and [Fe(CN)_6]^(3-)` ions
D. `K^(+) and [Fe(CN)_6]^(4-)` ions

Answer

To solve the problem, we need to analyze the reaction that occurs when potassium cyanide (KCN) is mixed with iron(II) cyanide (Fe(CN)₂).

### Step-by-Step Solution:

1. **Identify the Reactants:**
- We have potassium cyanide (KCN) and iron(II) cyanide (Fe(CN)₂).

2. **Write the Chemical Reaction:**
- When KCN is mixed with Fe(CN)₂, it can be represented as:
\[ 4 \text{KCN} + \text{Fe(CN)}_2 \rightarrow \text{K}_4\text{Fe(CN)}_6 + 4 \text{K}^+ + 2 \text{Fe}^{2+} \]
- Here, potassium cyanide reacts with iron(II) cyanide to form potassium ferrocyanide (K₄[Fe(CN)₆]) and potassium ions (K⁺) along with iron ions (Fe²⁺).

3. **Identify the Product:**
- The main product of the reaction is potassium ferrocyanide (K₄[Fe(CN)₆]), which is a complex ion.

4. **Testing for the Product:**
- Potassium ferrocyanide can be tested using a specific reagent. When potassium ferrocyanide is treated with a ferric ion (Fe³⁺), it forms a blue precipitate known as "Turnbull's Blue" or "Prussian Blue," which indicates the presence of ferrocyanide ions.

5. **Conclusion:**
- The resulting solution from mixing KCN and Fe(CN)₂ will give a positive test for ferrocyanide ions (Fe(CN)₆⁴⁻).

### Final Answer:
The resulting solution will give a test for **ferrocyanide ions (Fe(CN)₆⁴⁻)**.