Answer:
CO (carbon Dioxide)
Step-by-step explanation:
Fossil fuels such as coal and petroleum products contain carbon (C) and hydrogen (H). When they burn completely, carbon and hydrogen react with oxygen gas to produce carbon dioxide (CO₂) and water (H₂O).
But in incomplete burning, a portion of carbon that contained in fossil fuel is not completely oxidized. As a result carbon monoxide (CO) is produced.
The carbon monoxide is a poisonous gas that affects health. The maximum limit of carbon monoxide production allowed in flue products is 400 ppm (parts per million) and the gas flame produces 0 and 50 ppm of carbon monoxide.
Incomplete combustion results in the production of above 7,000 ppm of carbon monoxide. Such a high concentration of carbon monoxide is a health risk and can be fatal.