Which factor contributes to gasoline being classified as highly flammable?

Gasoline is classified as highly flammable due to its very low flashpoint. The flashpoint is the lowest temperature at which the vapors of a material can ignite when exposed to an open flame or spark. For gasoline, this flashpoint is typically around -40 degrees Fahrenheit (-40 degrees Celsius), meaning it can easily produce flammable vapors at room temperature. This characteristic is critical because it indicates the substance can readily form ignitable mixtures with the air, making it dangerous in ordinary conditions.

A low flashpoint is a primary indicator of a material's flammability, as it suggests that the liquid will generate vapor that can catch fire. Other factors, such as the rate of evaporation and vapor density, contribute to the overall behavior of gasoline when ignited, but the flashpoint stands out as the key measure defining its flammability hazard. The high boiling point, while relevant to the physical properties of gasoline, does not directly influence its classification as highly flammable in the same way that the flashpoint does.