What is a colorless and odorless gas produced by incomplete burning of fuel?

The correct answer is carbon monoxide, which is a colorless and odorless gas produced by the incomplete combustion of various fuels, such as gasoline, wood, coal, and natural gas. When these fuels do not burn completely due to insufficient oxygen, carbon monoxide is formed as a byproduct. This gas is particularly dangerous because it is difficult to detect without specialized equipment, making it a significant risk in environments where combustion takes place, such as homes with gas appliances, cars, and industrial settings.

Hydrogen, while colorless and odorless, is not produced through the incomplete combustion of fuels but rather can be created from various chemical processes, including electrolysis and natural gas reforming. Nitrogen dioxide is a reddish-brown gas with a distinctive sharp, acrid odor and is primarily produced from the burning of fossil fuels, particularly at high temperatures. Chlorofluorocarbons (CFCs) are synthetic compounds used primarily in refrigeration and aerosols, and they do not relate to incomplete combustion processes. Therefore, carbon monoxide is the only gas in this context that meets the criteria.