G2 Gas Fitter Practice Exam

What products result from incomplete combustion?

1. Oxygen and carbon dioxide

2. Carbon monoxide and soot

3. Nitrogen oxides

4. Hydrogen and methane

The correct answer is: Carbon monoxide and soot

Incomplete combustion occurs when there is not enough oxygen available for a fuel to react completely, resulting in the formation of products that are partially oxidized. In this scenario, carbon is not fully converted to carbon dioxide, which is a complete combustion product. Instead, it can produce carbon monoxide and soot (carbon in solid form). Carbon monoxide is a poisonous gas that can be hazardous when inhaled, as it binds tightly with hemoglobin in the blood, reducing the blood's ability to carry oxygen. Soot, on the other hand, is a black residue composed of fine carbon particles that can accumulate in chimneys and pose a fire hazard, as well as contribute to pollution. The other options represent different combustion products: oxygen and carbon dioxide result from complete combustion, while nitrogen oxides (which form during high-temperature combustion, particularly in internal combustion engines) and hydrogen and methane (which are fuels rather than combustion products) do not arise from incomplete combustion. Thus, the correct selection focuses on the harmful byproducts typically associated with insufficient oxygen during the burning of hydrocarbons.