Why is a brownish ppt. obtained in group II even if iron aluminium and chromium are absent?

Explanation

To answer the question of why a brownish precipitate is obtained in group II even if iron, aluminum, and chromium are absent, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Group II Cations**:
- Group II in qualitative analysis typically includes cations like lead (Pb²⁺), mercury (Hg²⁺), and bismuth (Bi³⁺). However, the question focuses on the formation of a brown precipitate.

2. **Role of Ammonium Chloride**:
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