G2 Gas Fitter Exam 2026 – 400 Free Practice Questions to Pass the Exam

The correct choice is centered on the importance of maintaining the right air-fuel ratio for ensuring an efficient and effective combustion process. The air-fuel ratio is the proportion of air to fuel that is used in combustion; it is crucial for achieving complete combustion.

When the air-fuel ratio is balanced, the combustion process generates optimal heat while minimizing harmful emissions. A correct ratio allows for sufficient oxygen to fully oxidize the fuel, which leads to a cleaner burn, improved efficiency, and safer operation of combustion equipment. If the mixture is too lean or too rich, it can lead to incomplete combustion, resulting in wasted fuel, increased emissions, and potentially harmful byproducts like carbon monoxide.

In contrast, an excessive amount of fuel can lead to a rich mixture, which may also lead to incomplete combustion and inefficient operation. High humidity can affect combustion efficiency but is not essential in the same way as the air-fuel ratio. Additionally, low temperatures can influence combustion efficiency but are not fundamental to the combustion process itself when compared to the correct air-fuel ratio.