O Levels Chemistry (5070)•5070/12/M/J/23
Explanation
Correct Statement on Air Pollution Control
Steps:
- Evaluate A: Catalytic converters oxidize CO to CO2, reduce NOx to N2, and convert hydrocarbons to CO2 and H2O.
- Evaluate B: Flue gas desulfurization (FGD) removes SO2 using calcium carbonate or oxide, not nitrate.
- Evaluate C: Photosynthesis equation 6CO2 + 6H2O → C6H12O6 + 6O2 shows CO2 absorption, not release.
- Evaluate D: Photochemical smog forms from NOx and VOCs reacting in sunlight; SO2 causes acid rain instead.
Why A is correct:
- Catalytic converters use platinum/rhodium catalysts to convert toxic exhaust gases (CO, NOx, HC) into less harmful ones (CO2, N2, H2O) per redox reactions.
Why the others are wrong:
- B: FGD employs calcium carbonate slurry to form gypsum, not calcium nitrate.
- C: Photosynthesis consumes CO2 to produce glucose and oxygen.
- D: SO2 contributes to sulfuric acid in smog but not photochemical reactions driven by sunlight on NOx/VOCs.
Final answer: A
Topic: Air quality and climate
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