Which of the following metals does not dissolve in concentrated `HNO_(3)` ?

Options

A. `Pb`
B. `Cu`
C. `Au`
D. `Hg`

Answer

To determine which of the following metals does not dissolve in concentrated HNO3 (Nitric Acid), we will analyze the reactions of each metal with concentrated HNO3: lead (Pb), copper (Cu), silver (Ag), and mercury (Hg).

### Step-by-Step Solution:

1. **Identify the Metals**: The metals in question are lead (Pb), copper (Cu), silver (Ag), and mercury (Hg).

2. **Reaction of Lead (Pb)**:
- When lead reacts with concentrated HNO3, it dissolves and forms lead oxide (PbO), nitrogen dioxide (NO2), and water (H2O).
- **Reaction**:
\[ \text{Pb} + 4\text{HNO}_3 \rightarrow \text{PbO} + 4\text{NO}_2 + 2\text{H}_2\text{O} \]
- Conclusion: Lead dissolves in concentrated HNO3.

3. **Reaction of Copper (Cu)**:
- Copper also reacts with concentrated HNO3, producing copper oxide (CuO), nitrogen dioxide (NO2), and water.
- **Reaction**:
\[ \text{Cu} + 4\text{HNO}_3 \rightarrow \text{CuO} + 4\text{NO}_2 + 2\text{H}_2\text{O} \]
- Conclusion: Copper dissolves in concentrated HNO3.

4. **Reaction of Silver (Ag)**:
- Silver does not react with concentrated HNO3, indicating that it does not dissolve.
- **Conclusion**: Silver does not dissolve in concentrated HNO3.

5. **Reaction of Mercury (Hg)**:
- Mercury reacts with concentrated HNO3, forming mercury oxide (HgO), nitrogen dioxide (NO2), and water.
- **Reaction**:
\[ \text{Hg} + 2\text{HNO}_3 \rightarrow \text{HgO} + 2\text{NO}_2 + \text{H}_2\text{O} \]
- Conclusion: Mercury dissolves in concentrated HNO3.

### Final Answer:
Among the metals listed, **silver (Ag)** does not dissolve in concentrated HNO3.

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