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🧪 Chemistry  ·  Environmental Chemistry  ·  NEET & JEE

The green-chemistry concept of atom economy rates a synthesis more favourably when:

Answer: A larger fraction of all reactant atoms ends up in the desired product.

  • A The percentage yield of the desired organic product is very high
  • B The reaction uses the fewest number of reagents
  • C A larger fraction of all reactant atoms ends up in the desired product
  • D The reaction is fastest

Correct answer: C. A larger fraction of all reactant atoms ends up in the desired product

Explanation: Atom economy measures how much of the reactant mass is incorporated into the useful product; a high atom economy means less waste, independent of the conventional percentage yield.

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 →