A chemical that will ignite spontaneously in air at 130 °F (54.4 °C) or below is described as:

• A. Pyrophoric
• B. Flammable liquid
• C. Explosive
• D. Reactive

Answer: (A)

Spontaneous ignition in air at a relatively low temperature is described by the term pyrophoric. These materials react rapidly with oxygen in the air and can ignite without any external flame or spark, even at room temperature or when only mildly warmed. The specified temperature of 130 °F (54.4 °C) or below reflects this behavior, making pyrophoric the best fit. A flammable liquid, on the other hand, needs an ignition source to ignite and has a defined flash point rather than igniting on its own in air. An explosive involves a rapid energy release, typically detonation, not just spontaneous ignition in air. Reactive is a broader label for substances that react vigorously with air or moisture, but it doesn’t specifically capture the spontaneous ignition characteristic described here.