In which of the following, ammonia is not present ?

Options

A. Nessler's reagent
B. Group reagent for the analysis of basic radicals of group IV
C. Group reagent for the analysis of basic radicals of group III
D. Tollen's reagent

Explanation

To determine in which of the following options ammonia is not present, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify Nessler's Reagent**:
- Nessler's reagent is represented by the formula \( K_2HgI_4 \).
- It is used primarily for the detection of ammonia in a solution.
- **Conclusion**: Nessler's reagent does not contain ammonia.

2. **Analyze Group Reagent 4**:
- The group reagent for Group 4 typically includes \( NH_4Cl \) (ammonium chloride), \( NH_4OH \) (ammonium hydroxide), and \( H_2S \) (hydrogen sulfide).
- Here, ammonia is present in the form of \( NH_4^+ \) ions.
- **Conclusion**: Ammonia is present in Group Reagent 4.

3. **Analyze Group Reagent 3**:
- The group reagent for Group 3 also includes \( NH_4Cl \) and \( NH_4OH \).
- In this case, ammonia is produced when these compounds are added to the solution until it smells like ammonia.
- **Conclusion**: Ammonia is present in Group Reagent 3.

4. **Analyze Tollen's Reagent**:
- Tollen's reagent consists of \( AgNO_3 \) (silver nitrate) and ammonia solution (\( NH_3 \)).
- Since ammonia is a component of Tollen's reagent, it is present.
- **Conclusion**: Ammonia is present in Tollen's reagent.

5. **Final Conclusion**:
- Among the options analyzed, only Nessler's reagent does not contain ammonia.
- Therefore, the correct answer is **Nessler's reagent**.