Final answer:
Gasoline is an example of a flammable liquid, known for its ease of ignition and use in creating highly flammable substances like Napalm. Sodium, though reactive, is not a flammable liquid, and Benzedrine is not related to this category of chemicals.
Step-by-step explanation:
An example of a flammable liquid would be gasoline. Gasoline is a commonly used fuel, and it is well-known for its ability to catch fire and burn easily in the presence of an ignition source. In contrast, sodium is a reactive metal that is stored under oil to prevent it from reacting with water or air, molten sulfur is not a liquid at room temperature, and Benzedrine is a brand name for amphetamine, which is not classified as a flammable liquid.
When discussing flammability, we are referring to a substance's chemical property which determines its ability to catch fire and sustain combustion. Gasoline is particularly notable for being used to create Napalm, an extremely flammable substance that turns gasoline into a jelly-like form to increase its stickiness and burning time.