Alberta Boilers Safety Association (ABSA) Practice Test

The flashpoint of a liquid is defined as the lowest temperature at which it can form enough vapor to ignite in the presence of an open flame or spark. This means that at the flashpoint, the liquid produces sufficient vapor that can mix with air and create a flammable mixture, which can ignite when exposed to an ignition source. Understanding the flashpoint is crucial for safety, handling, and storage of flammable liquids, as it helps to determine the conditions under which the liquid can pose a fire hazard.

In the context of the other options, the temperature at which a liquid will spontaneously combust refers to a higher temperature known as the autoignition temperature, not the flashpoint. The term "inert" in relation to vapors suggests that they do not react or ignite, which does not apply to the flashpoint concept; thus, the statement about vapors becoming inert is incorrect. Finally, the concept of molecular vibrations ceasing is related to absolute zero and is not applicable to the flashpoint of a liquid.