Final answer:
Ammonium azide is the substance from the provided options that is not a flammable liquid; it is a compound known for its explosive properties and not for being a liquid or its flammability.
Step-by-step explanation:
The question asks which substance is not an example of a flammable liquid. Among the options given, acetone, gasoline, and methanol are all flammable liquids and thus do represent examples of substances that can easily ignite and burn in air. However, ammonium azide is not a flammable liquid; it is actually a solid compound which is not known for its flammability but rather for its explosive properties when it decomposes. Therefore, B) ammonium azide is the correct answer to the question, as it does not represent a flammable liquid.
Flammable liquids have a characteristic of having a flash point and can ignite at relatively low temperatures. Examples of this include acetone and gasoline, which are used in various industrial and consumer products due to their ability to combust and provide energy. Methanol, too, is a commonly used solvent and fuel with flammable properties. Understanding the flammable nature of various substances is crucial in maintaining safety standards in various environments.