In rat poison, phosphorous is used in the form of `"___________"`

Explanation

**Step-by-Step Solution:**

1. **Identify the Allotropes of Phosphorus:**
- Phosphorus has three main allotropes: white phosphorus, black phosphorus, and red phosphorus.

2. **Determine the Allotrope Used in Rat Poison:**
- Among the three allotropes, white phosphorus is specifically used in rat poison.

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