Answer: heavy organic pollution.
- A very clean water
- B heavy organic pollution
- C high dissolved oxygen
- D very few bacteria
Correct answer: B. heavy organic pollution
Explanation: A high BOD means microbes are consuming a lot of oxygen to break down abundant organic waste.
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.