Final answer:
Solid fuels burn slowly as they usually ignite from the surface, liquid fuels need to vaporize before igniting and are quicker to ignite than solids but slower than gases, and gas fuels are the fastest to ignite due to their high mixability with air and low density.
Step-by-step explanation:
Physical Properties of Solid, Liquid, and Gas Fuels
When discussing the physical properties of solid, liquid, and gas fuels, it's crucial to understand that each state has distinct characteristics affecting their combustibility and behavior when heated. Solid fuels have a definite shape and volume, burning through a process that usually begins on the surface and progresses inward, making them slower to ignite and burn compared to gases. Liquid fuels have a definite volume but take the shape of their container; they can ignite more quickly than solids but generally not as fast as gases, as they often need to vaporize before burning. Gas fuels, which have neither definite shape nor volume, are the quickest to ignite since they mix with air easily and have low densities, allowing for rapid combustion once mixed with an oxidizer like oxygen.
The incorrect options state that solids and liquids decompose into non-flammable vapors at their ignition point, which is not true since they decompose into flammable vapors. Moreover, the statement saying that liquid fuels require the least amount of time to ignite is false; typically, gases ignite faster than liquids, given their ease of mixing with air and rapid flame propagation.