Air Pollution: Causes, Effects and Control · NCERT Biology

Which of the following is considered a 'secondary' air pollutant?

  1. Carbon monoxide (CO)
  2. Tropospheric ozone (O₃)
  3. Sulfur dioxide (SO₂)
  4. Suspended particulate matter (SPM)
Show answer and explanation

Correct answer: Tropospheric ozone (O₃)

Secondary pollutants are not emitted directly from sources but form in the atmosphere through chemical reactions between primary pollutants and other atmospheric components. Ozone (O₃) is a classic example formed in the presence of sunlight.

Difficulty: Medium Question 17 of 20

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