Normally, solubility of a crystalline solid increases with temperature. Does it increase uniformly in all cases? Name a substance whose solubility : initially increases then decreases with rise in temperature.

Explanation

### Step-by-Step Text Solution

1. **Understanding Solubility and Temperature Relationship**:
- Normally, the solubility of crystalline solids increases with an increase in temperature. However, this is not a universal rule and does not apply to all substances uniformly.

2. **Identifying the Exception**:
- We need to identify a substance whose solubility initially increases with temperature and then decreases. One such substance is **calcium sulfate (CaSO4)**.

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