Which term is correctly paired with the description 'an article capable of spontaneous ignition when exposed to air'?

• A. Pyrophoric
• B. Gun Powder
• C. Ammunition
• D. Cartridge

Answer: (A)

Spontaneous ignition in air describes a material that catches fire simply by being exposed to oxygen, without an external spark or flame. That is the property of a pyrophoric substance: it will ignite on contact with air due to rapid oxidation. This explains safety concerns and examples like white phosphorus, which must be stored under protective conditions. In contrast, gun powder is designed to burn only when initiated by a flame or heat source, not to ignite on its own in air. An ammunition or cartridge refers to a complete round, not to a reactive property of a material with air. Therefore, the term that matches the description is pyrophoric.