- A A gradual buildup of excess atmospheric carbon dioxide alone
- B SO2 and NOx reacting with water to form H2SO4 and HNO3
- C Gradual depletion of the protective stratospheric ozone layer
- D Heavy metal contamination accumulating gradually within rainwater
Correct answer: B. SO2 and NOx reacting with water to form H2SO4 and HNO3
Explanation: Acid rain: SO2 and NOx (from burning fossil fuels) react with water vapor to form sulfuric and nitric acids in rain.
Concept context
Levels of biodiversity, species richness patterns, threats (HIPPO), and conservation strategies. Always in NEET.