What is the lowest temperature at which a substance releases enough vapors to ignite?

The lowest temperature at which a substance releases enough vapors to ignite is known as the flash point. This critical temperature marks the point where the vapor concentration in the air is sufficient to form an ignitable mixture when exposed to an ignition source, such as a spark or flame. Understanding flash point is essential for fire safety and handling of flammable materials, as it helps assess the risks related to storage and use.

In contrast, the other terms, while related to combustion properties, refer to different concepts. The fire point, for instance, is the temperature at which a substance can sustain combustion, meaning it will continue to burn after being ignited. The flame point is not a standard term used in fire safety literature and may lead to confusion. The combustion point is generally used to describe the temperature at which a substance's combustion process begins in a broader context but does not specifically indicate the ignition of vapors. Therefore, flash point is the crucial term to understand the ignition risk associated with various substances.