Nitrate & Nitrite both give brown ring test, can be distinguish by -

Options

A. `HOSO_(2)NH_(2)` (Sulphonic acid)
B. `NH_(2)HgO.Hgl` ("Million base")
C. `FeSO_(4)`
D. None

Answer

To distinguish between nitrate and nitrite ions, which both give a brown ring test, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Brown Ring Test**:
- The brown ring test is a qualitative analysis method used to detect the presence of nitrate ions (NO3-) in a solution. When a solution containing nitrate is treated with iron(II) sulfate (FeSO4) and concentrated sulfuric acid (H2SO4), a brown ring forms at the interface of the two liquids.

2. **Identifying the Problem**:
- Both nitrate and nitrite ions can give a brown ring test, making it necessary to find a way to distinguish between them.

3. **Using Sulfonic Acid**:
- To differentiate between nitrate and nitrite ions, we can use sulfonic acid. When nitrite ions (NO2-) are present, they will react differently than nitrate ions in the presence of sulfonic acid.

4. **Performing the Test**:
- Add a few drops of sulfonic acid to the solution containing the suspected nitrate or nitrite ions.
- Observe the reaction. If a brown ring forms, it indicates the presence of nitrate ions. If no brown ring forms, it suggests the presence of nitrite ions.

5. **Conclusion**:
- The presence of a brown ring after adding sulfonic acid confirms the presence of nitrate ions, while the absence of a brown ring indicates nitrite ions.

### Final Answer:
To distinguish between nitrate and nitrite ions, one can use sulfonic acid, as it reacts differently with these ions.

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