Which one of the following can be used in place of `NH_(4)Cl` for identification of the third group radicals?

Options

A. NaCI
B. `(NH_(4))_(2)SO_(4)`
C. `(NH_(4))_(2)CO_(3)`
D. `NH_(4)NO_(3)`

Answer

To solve the question of which compound can be used in place of `NH4Cl` for the identification of the third group radicals, we need to understand the role of `NH4Cl` in this context.

### Step-by-Step Solution:

1. **Understanding the Role of NH4Cl**:
- `NH4Cl` provides ammonium ions (`NH4+`). These ions are crucial because they help suppress the ionization of ammonium hydroxide (`NH4OH`), allowing for the precipitation of third group radicals.

2. **Identifying the Third Group Radicals**:
- The third group radicals typically include cations such as `Fe^3+`, `Al^3+`, `Cr^3+`, etc. These ions can form precipitates with certain anions.

3. **Finding Alternatives to NH4Cl**:
- We need to find a compound that can also provide `NH4+` ions without causing precipitation of the third group radicals.

4. **Considering Other Ammonium Salts**:
- Ammonium sulfate (`(NH4)2SO4`) and ammonium carbonate (`(NH4)2CO3`) can be considered as alternatives. Both of these salts dissociate in solution to provide `NH4+` ions.

5. **Evaluating Precipitation**:
- When using ammonium sulfate, the sulfate ion (`SO4^2-`) can potentially precipitate with certain cations (like `Ba^2+`), which is not desirable for our purpose.
- Similarly, ammonium carbonate can lead to the formation of carbonate precipitates with some metals.

6. **Choosing the Best Alternative**:
- Ammonium nitrate (`NH4NO3`) is a suitable alternative because it provides `NH4+` ions without the risk of precipitating with common third group radicals. The nitrate ion (`NO3^-`) does not form insoluble salts with the third group cations.

7. **Conclusion**:
- Therefore, the best alternative to `NH4Cl` for the identification of third group radicals is `NH4NO3`.

### Final Answer:
**Ammonium nitrate (NH4NO3) can be used in place of NH4Cl for the identification of the third group radicals.**

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