Which element on reaction with `HNO_(3)` gives five different products

Options

A. Fe
B. Cu
C. Na
D. Zn

Answer

To determine which element reacts with nitric acid (HNO3) to produce five different products, we can analyze the reaction of copper with both dilute and concentrated nitric acid.

### Step-by-Step Solution:

1. **Identify the Element**: The element we are considering is **Copper (Cu)**.

2. **Reaction with Dilute HNO3**:
- When copper reacts with dilute nitric acid (HNO3), the reaction can be represented as:
\[ 3 \text{Cu} + 8 \text{HNO}_3 \rightarrow 3 \text{Cu(NO}_3\text{)}_2 + 2 \text{NO} + 4 \text{H}_2\text{O} \]
- Here, the products formed are:
- Copper(II) nitrate \((\text{Cu(NO}_3\text{)}_2)\)
- Nitric oxide \((\text{NO})\)
- Water \((\text{H}_2\text{O})\)

3. **Reaction with Concentrated HNO3**:
- When copper reacts with concentrated nitric acid, the reaction can be represented as:
\[ \text{Cu} + 4 \text{HNO}_3 \rightarrow \text{Cu(NO}_3\text{)}_2 + 2 \text{NO}_2 + 2 \text{H}_2\text{O} \]
- Here, the products formed are:
- Copper(II) nitrate \((\text{Cu(NO}_3\text{)}_2)\)
- Nitrogen dioxide \((\text{NO}_2)\)
- Water \((\text{H}_2\text{O})\)

4. **Total Products**:
- From the two reactions, we can summarize the products:
- From dilute HNO3: \(\text{Cu(NO}_3\text{)}_2\), \(\text{NO}\), \(\text{H}_2\text{O}\)
- From concentrated HNO3: \(\text{Cu(NO}_3\text{)}_2\), \(\text{NO}_2\), \(\text{H}_2\text{O}\)
- The unique products are:
- Copper(II) nitrate
- Nitric oxide
- Nitrogen dioxide
- Water
- However, since water is produced in both reactions, we can count it only once.

5. **Final Count of Unique Products**:
- The unique products formed from the reaction of copper with HNO3 are:
1. Copper(II) nitrate
2. Nitric oxide
3. Nitrogen dioxide
4. Water
- The fifth product can be considered as the gaseous nitrogen (N2) that may be produced under certain conditions, or other nitrogen oxides depending on the reaction conditions.

### Conclusion:
The element that reacts with HNO3 to give five different products is **Copper (Cu)**.