NEBOSH Practice Test

What is defined as the lowest temperature at which a substance can ignite when exposed to an ignition source?

1. Flashpoint

2. Autoignition Temperature

3. Combustion Point

4. Boiling Point

The correct answer is: Flashpoint

The concept of flashpoint refers specifically to the lowest temperature at which a substance, when heated, can form an ignitable mixture with air. At this temperature, the substance's vapors can ignite upon exposure to an ignition source, such as a spark or flame. Determining the flashpoint is crucial in assessing the fire hazards related to flammable liquids and helps in establishing safe handling and storage practices. The other terms mentioned indicate different properties of substances related to heat and combustion. For instance, the autoignition temperature is the temperature at which a substance ignites spontaneously without an external ignition source, while the combustion point refers to the temperature at which a substance will burn in air without a limit. The boiling point, on the other hand, is the temperature at which a substance changes from a liquid to a gas. Each term has its significance in fire safety and chemistry, but flashpoint specifically addresses the temperature necessary for ignition with an ignition source, making it the appropriate choice for this definition.