`CuSO_(4)+KCN(excess) to K_(3)[Cu(CN)_(4)]+(1)/(2)(CN)_(2)`

Options

A. For coloured ppt./Black ppt
B. For coloured solution.
C. for clear/colourless solution
D. For white ppt.

Answer

To solve the question regarding the reaction between CuSO₄ and KCN, we will analyze the reaction step by step.

### Step 1: Identify the Reactants
The reactants in the reaction are:
- Copper(II) sulfate (CuSO₄)
- Potassium cyanide (KCN), which is in excess

### Step 2: Write the Reaction
The reaction can be represented as:
\[ \text{CuSO}_4 + \text{KCN} \xrightarrow{\text{excess}} \text{K}_3[\text{Cu(CN)}_4] + \frac{1}{2} \text{CN}_2 \]

### Step 3: Analyze the Products
The products of the reaction include:
- Potassium tetra-cyanocuprate(II) complex, \( \text{K}_3[\text{Cu(CN)}_4] \)
- A small amount of cyanamide, \( \frac{1}{2} \text{CN}_2 \)

### Step 4: Determine the Solubility of the Complex
The complex \( \text{K}_3[\text{Cu(CN)}_4] \) is known to be soluble in water. This means that when it forms, it will not precipitate out of the solution.

### Step 5: Identify the Color of the Solution
The tetra-cyanocuprate(II) complex is a colorless complex. Therefore, when it dissolves in water, it will produce a clear and colorless solution.

### Conclusion
Based on the analysis, the reaction between CuSO₄ and excess KCN produces a clear and colorless solution.

### Final Answer
The answer is: **C. It will form a clear and colorless solution.**

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