What term describes any substance that will spontaneously ignite or explode upon exposure to an oxidizer?

• A. Pyrolytic Substance
• B. Hypergolic Material
• C. Spontaneous Combustion Substance
• D. Oxidizer-Sensitive Material

Answer: (B)

Hypergolic materials ignite spontaneously when they touch an oxidizer. The oxidizer provides the oxygen and drives an immediate, self-sustaining reaction, so no external ignition source is needed. This directly matches the idea of a substance that will spontaneously ignite or explode on exposure to an oxidizer. In contrast, pyrolytic substances ignite from heat causing decomposition, spontaneous combustion involves self-heating in air, and oxidizer-sensitive materials react with oxidizers but don’t necessarily ignite instantly on contact. Thus, the term that fits this behavior is hypergolic.