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 solve the question of which metal nitrate produces a gaseous product when reacted with KCN solution, we will analyze the reactions of each metal nitrate with KCN and identify any gaseous products formed.

### Step-by-Step Solution:

1. **Identify the Metal Nitrates**: The given options are:
- Cu(NO3)2 (Cupric nitrate)
- AgNO3 (Silver nitrate)
- Cd(NO3)2 (Cadmium nitrate)
- Pb(NO3)2 (Lead nitrate)

2. **Write the Reactions**:
- **For Cu(NO3)2**:
\[ \text{Cu(NO}_3\text{)}_2 + 4 \text{KCN} \rightarrow \text{Cu}_2\text{CN}_2 + 2 \text{KNO}_3 + \text{CN}_2(g) \]
Here, cyanogen gas (CN2) is produced.

- **For AgNO3**:
\[ \text{AgNO}_3 + \text{KCN} \rightarrow \text{AgCN} + \text{KNO}_3 \]
No gas is produced.

- **For Cd(NO3)2**:
\[ \text{Cd(NO}_3\text{)}_2 + 2 \text{KCN} \rightarrow \text{Cd(CN)}_2 + 2 \text{KNO}_3 \]
No gas is produced.

- **For Pb(NO3)2**:
\[ \text{Pb(NO}_3\text{)}_2 + 2 \text{KCN} \rightarrow \text{Pb(CN)}_2 + 2 \text{KNO}_3 \]
No gas is produced.

3. **Analyze the Results**:
- From the reactions, we see that only the reaction of cupric nitrate (Cu(NO3)2) with KCN produces a gaseous product (CN2). The other metal nitrates (AgNO3, Cd(NO3)2, and Pb(NO3)2) do not produce any gas when reacted with KCN.

4. **Conclusion**:
- The metal nitrate that produces a gaseous product when reacted with KCN solution is **Cu(NO3)2 (Cupric nitrate)**.

### Final Answer:
The answer is **Cu(NO3)2 (Cupric nitrate)**.

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