Nitrite `(NO_(2)^(Θ))` interfers in the ring -test of nitrate `(NO_(3)^(Θ))`. Some of the following reagent can be used for the removal of nitrite

Options

A. `NH_4Cl`
B. `(NH_(2))_(2) CS`(thiourea)
C. `NH_(2)SO_(3)H` (sulphamic acid)
D. None of these

Answer

To solve the problem of how to remove nitrite (NO₂⁻) that interferes with the ring test for nitrate (NO₃⁻), we can evaluate the reagents provided and their reactions with nitrite.

### Step-by-Step Solution:

1. **Identify the Reagents**: The question mentions several reagents that may be used to remove nitrite. We will evaluate each reagent's ability to react with nitrite.

2. **Evaluate Ammonium Chloride (NH₄Cl)**:
- When sodium nitrite (NaNO₂) is mixed with ammonium chloride (NH₄Cl), the reaction produces ammonium nitrite (NH₄NO₂) and sodium chloride (NaCl).
- Upon heating, ammonium nitrite decomposes to produce nitrogen gas (N₂) and water (H₂O).
- **Reaction**:
\[ \text{NaNO}_2 + \text{NH}_4\text{Cl} \rightarrow \text{NH}_4\text{NO}_2 + \text{NaCl} \]
\[ \text{NH}_4\text{NO}_2 \xrightarrow{\text{heat}} \text{N}_2 + \text{H}_2\text{O} \]
- **Conclusion**: Ammonium chloride can effectively remove nitrite.

3. **Evaluate Thiourea (NH₂CSNH₂)**:
- Thiourea reacts with nitrous acid (HNO₂), which can be generated from nitrite in the presence of sulfuric acid (H₂SO₄).
- The reaction produces sulfur dioxide (SO₂), nitrogen gas (N₂), and water.
- **Reaction**:
\[ \text{HNO}_2 + \text{NH}_2\text{CSNH}_2 \rightarrow \text{SO}_2 + \text{N}_2 + \text{H}_2\text{O} \]
- **Conclusion**: Thiourea can also be used to remove nitrite.

4. **Evaluate Sulphamic Acid (NH₂SO₃H)**:
- Sulphamic acid reacts with nitrite to convert it into nitrogen gas.
- The overall reaction results in the release of nitrogen gas and the formation of sulfuric acid (H₂SO₄) and water.
- **Reaction**:
\[ \text{NH}_2\text{SO}_3\text{H} + \text{NO}_2^- \rightarrow \text{N}_2 + \text{H}_2\text{SO}_4 + \text{H}_2\text{O} \]
- **Conclusion**: Sulphamic acid can also effectively remove nitrite.

5. **Final Conclusion**:
- All three reagents (Ammonium Chloride, Thiourea, and Sulphamic Acid) can be used to remove nitrite from a mixture containing nitrate. Therefore, the correct answer is that options 1, 2, and 3 can all be used for the removal of nitrite.

### Summary of the Answer:
The reagents that can be used for the removal of nitrite (NO₂⁻) are:
1. Ammonium Chloride (NH₄Cl)
2. Thiourea (NH₂CSNH₂)
3. Sulphamic Acid (NH₂SO₃H)