Which of the following acids attack(s) on copper and silver?

Options

A. dilute `HNO_(3)`
B. dilute `HCl`
C. conc. `H_(2)SO_(4)`
D. aqura regia

Answer

To determine which acids attack copper and silver, we will analyze each acid one by one based on their chemical properties and reactions with these metals.

### Step-by-Step Solution:

1. **Identify the Acids**: The acids we need to evaluate are:
- Dilute HNO3 (Nitric Acid)
- Dilute HCl (Hydrochloric Acid)
- Concentrated H2SO4 (Sulfuric Acid)
- Aqua Regia (a mixture of HNO3 and HCl)

2. **Evaluate Dilute HNO3**:
- Dilute HNO3 is a strong oxidizing agent.
- When copper reacts with dilute HNO3, it forms copper nitrate (Cu(NO3)2), nitrogen monoxide (NO), and water (H2O).
- The reaction can be represented as:
\[ \text{Cu} + 4 \text{HNO}_3 \rightarrow \text{Cu(NO}_3\text{)}_2 + 2 \text{NO} + 2 \text{H}_2\text{O} \]
- Silver also reacts with dilute HNO3 to form silver nitrate (AgNO3), nitrogen monoxide (NO), and water:
\[ 3 \text{Ag} + 4 \text{HNO}_3 \rightarrow 3 \text{AgNO}_3 + 2 \text{NO} + 2 \text{H}_2\text{O} \]
- **Conclusion**: Dilute HNO3 attacks both copper and silver.

3. **Evaluate Dilute HCl**:
- Dilute HCl does not affect copper and silver because both metals are below hydrogen in the reactivity series.
- They cannot displace hydrogen from HCl.
- **Conclusion**: Dilute HCl does not attack copper or silver.

4. **Evaluate Concentrated H2SO4**:
- Concentrated H2SO4 is also a strong oxidizing agent.
- Copper reacts with concentrated H2SO4 to form copper sulfate (CuSO4), sulfur dioxide (SO2), and water:
\[ \text{Cu} + 2 \text{H}_2\text{SO}_4 \rightarrow \text{CuSO}_4 + 2 \text{SO}_2 + 2 \text{H}_2\text{O} \]
- Silver reacts with concentrated H2SO4 to form silver sulfate (Ag2SO4), sulfur dioxide (SO2), and water:
\[ 2 \text{Ag} + \text{H}_2\text{SO}_4 \rightarrow \text{Ag}_2\text{SO}_4 + \text{SO}_2 + 2 \text{H}_2\text{O} \]
- **Conclusion**: Concentrated H2SO4 attacks both copper and silver.

5. **Evaluate Aqua Regia**:
- Aqua regia is a mixture of HNO3 and HCl in a 1:3 ratio, and it is a very strong oxidizing agent.
- It can oxidize both copper and silver.
- The reactions involve the formation of various nitrogen oxides and chlorine gas, which are strong oxidizing agents.
- **Conclusion**: Aqua regia attacks both copper and silver.

### Final Answer:
The acids that attack copper and silver are:
- Dilute HNO3
- Concentrated H2SO4
- Aqua Regia