Basic radical which gives Nessler's reagent test in which brown precipitate or brown colouration obtained

Explanation

To solve the question regarding the basic radical that gives a positive Nessler's reagent test resulting in a brown precipitate or brown coloration, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Nessler's Reagent**:
- Nessler's reagent is a solution of mercuric iodide (HgI₂) in potassium iodide (KI) and is used to detect the presence of ammonia (NH₃) in a solution.

2. **Identifying the Basic Radical**:
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