To combust solid or liquid fuels, they must reach which state?

For solid or liquid fuels to combust, they must transition to a gaseous state. This is because combustion is fundamentally a chemical reaction that requires fuel to combine with an oxidizer (usually oxygen in the air) to produce energy in the form of heat and light.

When solid fuels burn, they first undergo a process called pyrolysis, which converts them into gaseous products, along with some volatile compounds and ash. Similarly, liquid fuels must evaporate and vaporize before they can mix with air and ignite. In both cases, reaching a gaseous state is essential for effective combustion, as it allows for the necessary interaction between the fuel and the oxidizer.

The other states mentioned, like solid or liquid, cannot support the combustion process efficiently, as they do not permit the required chemical reactions to occur. Additionally, plasma state involves ionized gases at extremely high temperatures, which is not a normal condition necessary for typical fuel combustion processes. Thus, the necessity for solid and liquid fuels to achieve a gaseous state is a fundamental principle in understanding combustion dynamics.