Which of the following is not an Air Pollutant?

The correct answer is Option (3) → Nitrogen

Air pollutants are the substances that harm the air when they are released, mostly by burning coal, petrol and diesel and by industry.

Option (1) Sulphur oxide — An air pollutant. Oxides of sulphur (SO₂, SO₃) pollute the air.

Option (2) Carbon monoxide — An air pollutant. Carbon monoxide from burning fuel pollutes the air.

Option (3) Nitrogen — Not an air pollutant. Only the oxides of nitrogen are air pollutants, not nitrogen itself.

Option (4) Ammonia — An air pollutant. Ammonia pollutes both air and water.

Note: The given answer is as per the official NTA Answer Key. The book does not say in clear words that nitrogen is not an air pollutant. It only gives oxides of nitrogen, not nitrogen itself, among the air pollutants.