Answer: is decomposed by microorganisms.
- A never breaks down at all
- B is decomposed by microorganisms
- C is strongly radioactive
- D is always a heavy metal
Correct answer: B. is decomposed by microorganisms
Explanation: Biodegradable pollutants (e.g. sewage) can be broken down naturally by microbes, unlike persistent pollutants.
Classical smog is a reducing mixture of SO₂ and fog, while photochemical smog is an oxidising mixture generated by UV-driven reactions of NOx and hydrocarbons.
Concept context
Understand how human activities alter the atmosphere, water, and soil. Covers air pollutants, smog types, ozone depletion, acid rain, greenhouse effect, water and soil pollution, and the principles of green chemistry.