Which of the following will be reduced in air in a city forest when a lot of dust and fly ash in emitted by a coal-based factory in the vicinity?
nitrogen
carbon dioxide
oxygen
water vapour

Correct Answer: C. oxygen

Explanation: The various air pollutants discharged by motor vehicles and by the burning of fossil fuel in a factory are carbon dioxide, carbon monoxide, nitrogen oxides and smoke. It results in a decrease in the amount of oxygen in the air.