Why is white phosphorus kept under water ?

Explanation

**Step-by-Step Solution:**

1. **Understanding White Phosphorus**: White phosphorus is a molecular form of phosphorus, represented as P4. It is known for its high reactivity and is a waxy solid that can ignite spontaneously in air.

2. **Ignition Temperature**: The ignition temperature of white phosphorus is approximately 303 Kelvin (30 degrees Celsius). This means that at or above this temperature, white phosphorus can catch fire when exposed to air.

3. **Reactivity with Oxygen**: When white phosphorus is exposed to oxygen in the air, it reacts to form phosphorus pentoxide (P4O10). This reaction is highly exothermic, meaning it releases a significant amount of heat, which can lead to combustion.

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