Which of the following is a required condition for complete combustion?

Complete combustion is a chemical reaction where fuel burns in the presence of sufficient oxygen, resulting in the production of water vapor and carbon dioxide as its primary outputs. For combustion to be complete, several conditions must be met, and the presence of heat is essential.

Heat serves as the initial energy source that enables fuel to reach its ignition temperature, which is the minimum temperature required to sustain combustion. Once ignition occurs, the heat generated during the reaction continues to promote further combustion as long as there is a consistent supply of fuel and sufficient oxygen. Hence, without the presence of heat, the combustion process cannot initiate, making it a critical requirement for achieving complete combustion.

In contrast, high fuel concentration may lead to incomplete combustion if there is not enough oxygen to react with all of the fuel present. Low air temperature can hinder the combustion process by not being sufficient enough to sustain the ignition. Similarly, an excess of carbon dioxide is often a byproduct of combustion, indicating that there may not be enough oxygen for complete combustion to occur, thus not contributing positively to the combustion efficiency.

Therefore, the presence of heat is indeed the necessary condition for complete combustion to take place.