Gas Fitter Practice Test

Carbon monoxide (CO) is produced from the incomplete combustion of which substance?

1. Oxygen

2. Air

3. Soot

4. Hydrocarbons

The correct answer is: Hydrocarbons

Carbon monoxide (CO) is produced from the incomplete combustion of hydrocarbons. Hydrocarbons, which are organic compounds made up of carbon and hydrogen, serve as the primary fuels in many combustion processes. When hydrocarbons undergo combustion in a limited supply of oxygen, instead of being fully converted to carbon dioxide (CO2) and water (H2O), the process may produce carbon monoxide, which is a toxic gas. The incomplete combustion occurs when there isn’t enough oxygen available to allow the fuel to combust completely. In this scenario, the carbon atoms in the hydrocarbons do not fully oxidize, leading to the formation of carbon monoxide. This is particularly dangerous because carbon monoxide is colorless, odorless, and can lead to serious health hazards for humans and animals when accumulated in the environment or enclosed spaces. While oxygen and air are essential for the combustion process, they do not produce carbon monoxide themselves; rather, they are involved in the combustion reactions. Soot is a byproduct of incomplete combustion and consists of carbon particles, but it is not a substance that directly leads to the production of carbon monoxide. Therefore, hydrocarbons are specifically identified as the source of this toxic gas when combustion conditions are inadequate.