Benzene react with nitrating mixture (conc. `HNO_(3)` and conc `H_(2)SO_(4)`.) to produce nitrobenzene. In the nitrating mixture, `HNO_(3)` acts as a

Options

A. Base
B. Acid
C. Reducing agent
D. Catalyst

Answer

To solve the question regarding the role of nitric acid (HNO₃) in the nitrating mixture with concentrated sulfuric acid (H₂SO₄) that produces nitrobenzene from benzene, we can break down the process step by step.

### Step-by-Step Solution:

1. **Understanding the Nitrating Mixture**:
- The nitrating mixture consists of concentrated nitric acid (HNO₃) and concentrated sulfuric acid (H₂SO₄).
- This combination is used to introduce a nitro group (-NO₂) into benzene.

2. **Role of Sulfuric Acid**:
- Sulfuric acid is a strong acid and acts as a dehydrating agent. It helps in the generation of the nitronium ion (NO₂⁺), which is the active electrophile in this reaction.

3. **Formation of the Nitronium Ion**:
- When concentrated nitric acid is mixed with concentrated sulfuric acid, sulfuric acid donates a proton (H⁺) to nitric acid.
- The reaction can be represented as:
\[ \text{HNO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{NO}_2^+ + \text{HSO}_4^- + \text{H}_2\text{O} \]
- Here, the nitric acid loses a water molecule and forms the nitronium ion (NO₂⁺), which is a potent electrophile.

4. **Role of Nitric Acid**:
- In this reaction, nitric acid (HNO₃) acts as a base because it accepts a proton (H⁺) from sulfuric acid.
- By accepting a proton, it facilitates the formation of the nitronium ion.

5. **Conclusion**:
- Therefore, in the nitrating mixture, nitric acid (HNO₃) acts as a base.

### Final Answer:
In the nitrating mixture, HNO₃ acts as a **base**.