Which description of spontaneous combustion is correct?

Which description of spontaneous combustion is correct?

• A. A rapid reaction producing instant flames
• B. A physical process with no heat release
• C. A slow chemical reaction that generates heat
• D. A reversible phase transition that consumes heat

Answer: (C)

Spontaneous combustion happens when a material undergoes slow oxidation inside itself, releasing heat gradually. If that heat isn’t carried away fast enough, the temperature climbs until it reaches the material’s ignition point and it catches fire without an external flame. This is a slow exothermic chemical process, not a rapid flame, not a physical change with no heat release, and not a reversible phase transition that consumes heat. Because it hinges on heat buildup from a slow chemical reaction, this description best fits spontaneous combustion.

Spontaneous combustion happens when a material undergoes slow oxidation inside itself, releasing heat gradually. If that heat isn’t carried away fast enough, the temperature climbs until it reaches the material’s ignition point and it catches fire without an external flame. This is a slow exothermic chemical process, not a rapid flame, not a physical change with no heat release, and not a reversible phase transition that consumes heat. Because it hinges on heat buildup from a slow chemical reaction, this description best fits spontaneous combustion.