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🧪 Chemistry  ·  Environmental Chemistry  ·  NEET & JEE

The process by which excess plant nutrients cause dense algal growth and later oxygen depletion is:

Answer: eutrophication.

  • A eutrophication
  • B sublimation
  • C vulcanisation
  • D saponification

Correct answer: A. eutrophication

Explanation: Eutrophication is nutrient over-enrichment leading to algal blooms and subsequent oxygen loss.

Classical (London) SmogSources: coal burningSO₂ + particulates + fogReducing typeConditions: cold, humid,early morning, winterVisibility: very low (fog)London, 1952 - ~4000 deathsHarms: eyes, lungs, bronchitisPhotochemical (LA) SmogSources: vehicles, industriesNOx + hydrocarbons + UVOxidising typeConditions: warm, sunny,afternoon, summerProducts: O₃, PAN, acroleinLos Angeles (common in cities)Harms: eyes, rubber cracking

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.

Read the full Environmental Chemistry notes →