At times warming is suggested while precipitating group V cation. Explain.

Explanation

### Step-by-Step Solution:

1. **Understanding Group V Cations**:
- Group V cations in qualitative analysis typically include cations like calcium (Ca²⁺), barium (Ba²⁺), and magnesium (Mg²⁺). These cations can be precipitated using ammonium carbonate ((NH₄)₂CO₃) in the presence of ammonium chloride (NH₄Cl).

2. **Role of Ammonium Carbonate**:
- Ammonium carbonate is used to precipitate these cations. However, it often contains impurities, particularly bicarbonate ions (HCO₃⁻), which can affect the precipitation process.

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