All nitrates on heating with conc. `H_(2)SO_(4)` in presence of paper pellet evolve `NO_(2)` gas. The function of the paper pellet is `:`

Options

A. reduce `HNO_(3)` to `N_(2)`
B. to reduce `HNO_(3)` to `NO`
C. to reduce `HNO_(3)` to `NO_(2)`
D. to reduce `HNO_(3)` to `NH_(3)`

Explanation

To solve the question regarding the function of the paper pellet when nitrates are heated with concentrated sulfuric acid (H₂SO₄), we can break down the process step by step.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
When nitrates (like sodium nitrate, potassium nitrate, etc.) are heated with concentrated sulfuric acid, they decompose to produce nitrogen dioxide (NO₂) gas.

2. **Role of Concentrated H₂SO₄**:
Concentrated sulfuric acid acts as a dehydrating agent and facilitates the breakdown of nitrates. It helps in the formation of nitric acid (HNO₃) which subsequently decomposes to produce NO₂.

3. **Inclusion of Paper Pellet**:
The paper pellet is primarily made of carbon (cellulose). When it is included in the reaction, it can react with the nitric acid formed during the decomposition of the nitrate.

4. **Reduction Reaction**:
The carbon in the paper pellet acts as a reducing agent. It reduces the nitrogen in nitric acid (HNO₃) from an oxidation state of +5 (in HNO₃) to +4 (in NO₂). This reduction process is crucial as it allows the evolution of NO₂ gas.

5. **Oxidation State Changes**:
- In nitric acid (HNO₃), nitrogen has an oxidation state of +5.
- In nitrogen dioxide (NO₂), nitrogen has an oxidation state of +4.
- The carbon from the paper pellet gets oxidized in the process.

6. **Conclusion**:
Therefore, the function of the paper pellet is to act as a reducing agent that reduces nitric acid (HNO₃) to nitrogen dioxide (NO₂), while itself being oxidized.

### Final Answer:
The function of the paper pellet is to reduce HNO₃ to NO₂.

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