Which of the following phosphorus is the most reactive?

Options

A. Red phosphorus
B. White phosphorus
C. Scarlet phosphorus
D. Violet phosphorus

Explanation

To determine which allotrope of phosphorus is the most reactive, we need to analyze the properties of the different allotropes: red phosphorus, white phosphorus, and scarlet phosphorus.

### Step-by-Step Solution:

1. **Identify the Allotropes**: The question provides three allotropes of phosphorus: red phosphorus, white phosphorus, and scarlet phosphorus. We need to evaluate their reactivity.

2. **Properties of White Phosphorus**:
- White phosphorus (P4) is known to be the most reactive allotrope of phosphorus.
- It is highly volatile, least dense, and most toxic among the allotropes.
- White phosphorus can ignite spontaneously in air, which indicates its high reactivity.

3. **Properties of Red Phosphorus**:
- Red phosphorus is more stable than white phosphorus and does not ignite in air at room temperature.
- It has a polymeric structure, which makes it less reactive compared to white phosphorus.

4. **Properties of Scarlet Phosphorus**:
- Scarlet phosphorus is a less common allotrope and is also more stable than white phosphorus.
- Its reactivity is similar to that of red phosphorus, making it less reactive than white phosphorus.

5. **Conclusion**: Based on the properties discussed, white phosphorus is the most reactive allotrope of phosphorus due to its high volatility and tendency to react readily with oxygen and other substances.

### Final Answer:
The most reactive phosphorus is **white phosphorus**.

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