What physical property of a liquid can greatly affect its flammability?

The flash point of a liquid is a critical physical property that significantly affects its flammability. It is defined as the lowest temperature at which a liquid can vaporize to form an ignitable mixture in air. When a liquid reaches its flash point, it emits enough vapor to ignite when exposed to an open flame or spark. Therefore, the flash point directly indicates the risk of combustion and the potential for a fire hazard associated with the liquid.

In practical terms, liquids with lower flash points are considered more flammable because they can produce ignitable vapors at relatively low temperatures, increasing the chances of accidental ignition in various environments. Understanding the flash point is essential for fire safety, as it guides the safe handling, storage, and use of flammable liquids to minimize fire risks.