Which metal does not form nitrate when heated with conc `HNO_(3)`:

Options

A. Zn
B. Mg
C. Sn
D. Pb

Answer

To determine which metal does not form a nitrate when heated with concentrated nitric acid (HNO3), we will analyze the reactions of each metal listed: zinc, magnesium, tin, and lead.

### Step-by-Step Solution:

1. **Identify the Metals**: The metals given in the question are zinc (Zn), magnesium (Mg), tin (Sn), and lead (Pb).

2. **Reaction of Zinc with Concentrated HNO3**:
- When zinc is heated with concentrated nitric acid, the reaction is:
\[ \text{Zn} + 2\text{HNO}_3 \rightarrow \text{Zn(NO}_3\text{)}_2 + \text{NO}_2 + \text{H}_2\text{O} \]
- **Conclusion**: Zinc forms zinc nitrate (Zn(NO3)2).

3. **Reaction of Magnesium with Concentrated HNO3**:
- When magnesium is heated with concentrated nitric acid, the reaction is:
\[ \text{Mg} + 2\text{HNO}_3 \rightarrow \text{Mg(NO}_3\text{)}_2 + \text{H}_2 \]
- **Conclusion**: Magnesium forms magnesium nitrate (Mg(NO3)2).

4. **Reaction of Tin with Concentrated HNO3**:
- When tin is heated with concentrated nitric acid, the reaction is:
\[ \text{Sn} + 4\text{HNO}_3 \rightarrow \text{SnO}_2 + 4\text{NO}_2 + 2\text{H}_2\text{O} \]
- **Conclusion**: Tin does not form a nitrate; instead, it forms tin oxide (SnO2) and nitrogen dioxide (NO2).

5. **Reaction of Lead with Concentrated HNO3**:
- When lead is heated with concentrated nitric acid, the reaction is:
\[ \text{Pb} + 2\text{HNO}_3 \rightarrow \text{Pb(NO}_3\text{)}_2 + \text{NO}_2 + \text{H}_2\text{O} \]
- **Conclusion**: Lead forms lead nitrate (Pb(NO3)2).

6. **Final Conclusion**:
- Among the metals analyzed, only **tin (Sn)** does not form a nitrate when heated with concentrated nitric acid. Therefore, the correct answer is **tin**.

### Answer:
The metal that does not form a nitrate when heated with concentrated nitric acid is **tin (Sn)**.