Answer: Rapid algal growth followed by oxygen depletion when the algae decay.
- A Increase in dissolved oxygen supporting fish
- B Rapid algal growth followed by oxygen depletion when the algae decay
- C A rise in lake water pH to strongly basic values
- D Precipitation of all dissolved nutrients as insoluble metal salts
Correct answer: B. Rapid algal growth followed by oxygen depletion when the algae decay
Explanation: Nutrient enrichment causes algal blooms; when the algae die, their decomposition by bacteria consumes dissolved oxygen, killing fish and other aquatic organisms.
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.