Which physical property indicates how easily a fuel can ignite?

The physical property that indicates how easily a fuel can ignite is represented by several factors, including flashpoint, ignition temperature, and flammable limits. Each of these properties contributes important information regarding the behavior of a fuel in the presence of a heat source.

Flashpoint is the lowest temperature at which a fuel can vaporize to form an ignitable mixture in the air. This means that if the fuel is heated to this temperature, it can produce enough vapor to ignite when mixed with air. Thus, a lower flashpoint indicates a higher likelihood of ignition.

Ignition temperature, also known as autoignition temperature, is the minimum temperature required for a fuel to ignite without an external spark or flame. This property reflects the energy needed to initiate combustion.

Flammable limits refer to the concentration range of a fuel in air that will support combustion. If the concentration falls outside these limits, the fuel will not ignite, regardless of the ignition source.

Since all three of these properties are crucial for understanding how easily a fuel can ignite, the correct answer encompasses all of them, making it comprehensive in assessing fuel ignition potential.