In what state must a fuel be for combustion to occur?

For combustion to occur, a fuel must be in a vapor state. This is because combustion is a chemical reaction that requires the fuel to mix with oxygen, and this reaction can only take place effectively when the fuel molecules are in a gaseous form.

In the case of liquid and solid fuels, they must first be converted into vapor to ignite and sustain combustion. While some solid and liquid fuels can burn at elevated temperatures, they need to evaporate or produce gas in order to mix with air and react with oxygen. For this reason, the vapor state is critical for the combustion process to begin and continue.

The gaseous state of a fuel is also important, as it allows for the necessary reactions to take place efficiently. Therefore, the vapor state facilitates the essential mixture of fuel and oxygen required for fire to ignite and maintain its burning.