American Chemical Society (ACS) Laboratory Safety Practice Test

A chemical marked as flammable has the key characteristic of being able to ignite very quickly. This means that it can easily catch fire when exposed to an open flame, spark, or even high temperatures. Flammable materials have a low flash point, which is the temperature at which they can form ignitable mixtures with air. This makes them particularly hazardous in laboratory and industrial settings, as they require strict safety protocols to prevent ignition and fire hazards.

In contrast, other characteristics outlined in the other options, while important, do not reflect the specific nature of flammability. For instance, some flammable substances may indeed be reactive with air, but this is not universally true for all flammable substances. Similarly, flammable materials are not considered safe for use with open flames, and they may also have various boiling points that do not necessarily relate to their flammable properties. Thus, understanding the quick ignition potential is crucial for handling, storing, and using such chemicals safely in any environment.