Which of the following metal nitrate produces gaseous product when reacts with KCN solution?

Options

A. `Cu(NO_(3))_(2)`
B. `AgNO_(3)`
C. `Cd(NO_(3))_(2)`
D. `Pb(NO_(3))_(2)`

Explanation

To determine which metal nitrate produces a gaseous product when it reacts with potassium cyanide (KCN), we will analyze the reactions of the given metal nitrates with KCN step by step.

### Step 1: Identify the Metal Nitrates
The metal nitrates we need to consider are:
1. Copper nitrate (Cu(NO3)2)
2. Silver nitrate (AgNO3)
3. Cadmium nitrate (Cd(NO3)2)
4. Lead nitrate (Pb(NO3)2)

### Step 2: Reaction of Copper Nitrate with KCN
When copper nitrate reacts with potassium cyanide, the reaction can be written as:
\[ \text{Cu(NO}_3\text{)}_2 + 4 \text{KCN} \rightarrow 2 \text{KNO}_3 + \text{Cu(CN)}_2 + \text{C}_2\text{N}_2 \]
Here, cyanogen (C2N2) is produced as a gaseous product.

### Step 3: Reaction of Silver Nitrate with KCN
For silver nitrate, the reaction is:
\[ \text{AgNO}_3 + 2 \text{KCN} \rightarrow \text{K}_2\text{Ag(CN)}_2 + \text{KNO}_3 \]
In this case, no gaseous product is formed.

### Step 4: Reaction of Cadmium Nitrate with KCN
When cadmium nitrate reacts with KCN, the reaction is:
\[ \text{Cd(NO}_3\text{)}_2 + 4 \text{KCN} \rightarrow \text{Cd(CN)}_2 + 2 \text{KNO}_3 \]
Again, no gaseous product is produced.

### Step 5: Reaction of Lead Nitrate with KCN
For lead nitrate, the reaction is:
\[ \text{Pb(NO}_3\text{)}_2 + 2 \text{KCN} \rightarrow \text{Pb(CN)}_2 + 2 \text{KNO}_3 \]
This reaction also does not yield any gaseous product.

### Conclusion
After analyzing all the reactions, we find that only copper nitrate (Cu(NO3)2) produces a gaseous product (cyanogen) when it reacts with potassium cyanide (KCN).

### Final Answer
The metal nitrate that produces a gaseous product when it reacts with KCN solution is **Copper Nitrate (Cu(NO3)2)**.

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