Question

White phosphorous burns spontaneously in air because it has a low ___________.

Answer 1

Ignition temperature: The lowest temperature at which a substance starts to burn.

1. White phosphorous is a highly reactive compound. When it comes in contact with air, it ignites at about 30^o C in moist air and starts burning.
2. This is because of its low ignition temperature. It is usually stored under in water, to prevent exposure to the air.

Therefore, White phosphorous burns spontaneously in air because it has a low Ignition temperature.