The source of carbon(II)oxide that acts as air pollutant is

Analyze the question: It asks for the source of carbon(II) oxide (CO) that acts as an air pollutant, so we need the main process that releases CO into the atmosphere in harmful amounts.

Concept: Carbon(II) oxide forms when carbon-containing materials burn in a limited supply of oxygen (incomplete combustion):

2C + O₂ → 2CO (limited oxygen)

Compare this with complete combustion, which gives carbon(IV) oxide:

C + O₂ → CO₂ (plentiful oxygen)

CO is toxic because it binds to haemoglobin in the blood, forming carboxyhaemoglobin. This stops the blood from carrying oxygen properly.

Check each option:

• A. Photochemical smog: This is a result of pollution (nitrogen oxides and hydrocarbons reacting in sunlight). It is not a source of CO.
• B. Respiration: This releases CO₂, not CO, and it is a natural process.
• C. Combustion of fuel: Car engines, generators (very common in Nigeria), and burning of wood, charcoal and kerosene release CO through incomplete combustion. This is the main source.
• D. Decomposition of sewage: This mainly produces methane, hydrogen sulphide and ammonia, not CO.

Answer: The source of CO as an air pollutant is combustion of fuel, which is option C.

Tip: Remember "CO = Choked Oxygen". CO comes from incomplete burning, such as vehicle exhaust and generator fumes. CO₂ comes from respiration and complete combustion. Never run a generator in a closed room, because CO poisoning can be fatal.