What is a spontaneously combustible material?

What is a spontaneously combustible material?

• A. A material that is air reactive.
• B. A material that requires an external flame to ignite.
• C. A material that only ignites underwater.
• D. A material that is non-flammable.

Answer: (A)

Spontaneously combustible materials ignite because of heat produced by their own reaction with air, not from an external flame. Oxidation inside the material can generate heat, and if that heat isn’t able to escape, the temperature rises until ignition occurs. That self-heating in air is what makes them spontaneously combustible, so the best description is that they are air reactive. This is different from materials that need an external flame to ignite, which only burn once you provide a flame or spark. It’s also not about materials that ignite underwater, and it certainly isn’t about materials that are non-flammable.

Spontaneously combustible materials ignite because of heat produced by their own reaction with air, not from an external flame. Oxidation inside the material can generate heat, and if that heat isn’t able to escape, the temperature rises until ignition occurs. That self-heating in air is what makes them spontaneously combustible, so the best description is that they are air reactive.

This is different from materials that need an external flame to ignite, which only burn once you provide a flame or spark. It’s also not about materials that ignite underwater, and it certainly isn’t about materials that are non-flammable.