Chemistry study notes
Maintaining Air Quality
Connect atmospheric substances to their sources, effects and possible solutions.
O-Level 5086 / 5088 (2026) / SEC G3 K326 / K328 (2027)
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12. Maintaining Air Quality (5086 / 5088 / K326 / K328). Use the outcome map to find the explanation for a particular syllabus requirement.
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12(a) Describe dry-air composition
- 78% nitrogen
- 21% oxygen
- Remainder noble gases, mainly argon, and CO2
12(b) Name atmospheric pollutants
- CO, CH4, NO, NO2, O3, SO2, unburned hydrocarbons
12(c) Identify pollutant sources
- CO from incomplete carbon-fuel combustion
- NOx from lightning and engines
- SO2 from volcanoes and fossil fuels
12(d) Explain pollutant effects
- CO toxicity
- NO2/SO2 acid rain
- Respiration and buildings
12(e) Explain the carbon cycle
- Photosynthesis
- Respiration
- Combustion
- Regulation of atmospheric CO2
12(f) Explain greenhouse-gas effects
- CO2 and CH4 sources
- Global warming
- Extreme weather and melting polar ice