The main difference between primary air pollutants and secondary air pollutants is best captured by which statement?
APrimary pollutants are released directly into the atmosphere, while secondary pollutants are formed by chemical reactions in the atmosphere
BThe best example of a primary air pollutant is carbon dioxide released from burning of coal
CThe best example of a secondary air pollutant is ozone produced in photochemical smog
DAll of the above ✓ Correct
Correct answer: (D) All of the above
Explanation
Primary pollutants enter the air directly from a source while secondary ones form through reactions in the atmosphere, capturing the core distinction.
Carbon dioxide from coal burning is a textbook primary pollutant released straight into the air.
Ozone in photochemical smog is a classic secondary pollutant formed by sunlight-driven reactions.
Each of these descriptions is individually accurate about the two classes of pollutants.
Together they define the difference and give a valid example of each type.
Peroxyacyl nitrates are another well-known secondary pollutant of photochemical smog.
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