The ratio of the number of water of crystallization in gypsum and that in plaster of Paris is _____

Explanation

To solve the question regarding the ratio of the number of water of crystallization in gypsum and plaster of Paris, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Chemical Formulas**:
- Gypsum: The chemical formula for gypsum is \( \text{CaSO}_4 \cdot 2\text{H}_2\text{O} \).
- Plaster of Paris: The chemical formula for plaster of Paris is \( \text{CaSO}_4 \cdot \frac{1}{2}\text{H}_2\text{O} \) or \( \text{CaSO}_4 \cdot 0.5\text{H}_2\text{O} \).

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