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Difficulty: HardComposition and Pollution of Air

Match each atmospheric pollutant or component in Column I with its corresponding chemical mode of action or environmental transformation mechanism in Column II.

  • Carbon monoxide (CO\text{CO})Binds irreversibly to Fe2+\text{Fe}^{2+} in hemoglobin to form carboxyhemoglobin, preventing oxygen transport
  • Sulfur dioxide (SO2\text{SO}_2)Undergoes atmospheric oxidation to form an acid anhydride that causes structural degradation of trioxocarbonate(IV) minerals
  • Chlorofluorocarbons (CFCs\text{CFCs})Undergoes solar UV photolysis releasing chlorine radicals that catalytically decompose stratospheric ozone
  • Nitrogen dioxide (NO2\text{NO}_2)Absorbs solar radiation and dissociates into atomic oxygen, initiating ground-level ozone and photochemical smog formation

Answer

Carbon monoxide matches with irreversible hemoglobin binding; Sulfur dioxide matches with oxidation to an acid anhydride causing limestone corrosion; Chlorofluorocarbons match with UV-induced photolysis producing chlorine radicals; Nitrogen dioxide matches with solar photolysis initiating photochemical smog.
Each atmospheric pollutant is accurately matched to its chemical mechanism: carbon monoxide forms carboxyhemoglobin in blood, sulfur dioxide forms acid anhydrides causing marble/limestone corrosion, chlorofluorocarbons generate ozone-depleting chlorine radicals under UV radiation, and nitrogen dioxide photolyzes in sunlight to drive photochemical smog formation.

Step-by-Step Solution

1
Analyze Carbon monoxide (CO\text{CO})
It readily binds to blood hemoglobin to form carboxyhemoglobin.
CO\text{CO} toxicological impact relies on inhibiting cellular respiration by reducing oxygen transport.
2
Analyze Sulfur dioxide (SO2\text{SO}_2)
It oxidizes to SO3\text{SO}_3 (sulfur trioxide, an acid anhydride), forming sulfuric acid rain.
Acid rain dissolves building materials containing calcium carbonate (CaCO3\text{CaCO}_3).
3
Analyze Chlorofluorocarbons (CFCs\text{CFCs})
High-energy solar ultraviolet radiation breaks C-Cl\text{C-Cl} bonds in CFCs\text{CFCs}, producing free chlorine radicals.
Chlorine radicals act as catalysts in the breakdown of stratospheric ozone molecules into oxygen gas.
4
Analyze Nitrogen dioxide (NO2\text{NO}_2)
In the troposphere, NO2\text{NO}_2 absorbs near-UV sunlight, splitting into NO\text{NO} and atomic oxygen (O\text{O}).
Atomic oxygen combines with O2\text{O}_2 to form tropospheric ozone, a key ingredient in photochemical smog.

Key Concept

Chemical transformations and atmospheric impacts of primary air pollutants
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Topics

Composition and Pollution of Air

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