Pollution from alkane combustion in engines

Steps:

• Alkanes like petrol burn in engines, producing CO, NOₓ, and unburnt hydrocarbons as pollutants.
• Assess each option against known engine emissions and pollution processes.
• Eliminate A, B, C for factual errors in fuel use or converter function.
• Confirm D matches atmospheric chemistry of smog formation.

Why D is correct:

• Unburnt hydrocarbons (VOCs from alkanes) and NO react via photochemical oxidation in sunlight, forming ozone and smog per the reaction: VOC + NO + O₂ + hv → NO₂ + peroxy radicals → O₃ + secondary pollutants.

Why the others are wrong:

• A: CH₄ (methane) is not the primary alkane fuel in car engines; petrol (C₅–C₁₂ alkanes) is used, and it reacts mainly with O₂, not directly with N₂.
• B: Catalytic converters remove NOₓ (including NO), CO, and hydrocarbons, but the statement omits hydrocarbons.
• C: Converters target CO, NOₓ, and hydrocarbons; SO₂ (from sulfur impurities) is not primarily removed by them.

Final answer: D