A-LevelChemistryReaction kineticsOct/Nov 2021Paper 1 Q111 Mark
NO and NO2 are both present in the lower atmosphere as pollutants. The reaction sequence shows the production of ozone from oxygen in the lower atmosphere. This sequence repeats many times. NO2(g) → NO(g) + O(g) NO(g) + ½O2(g) → NO2(g) O2(g) + O(g) → O3(g) Which statement about this reaction sequence is correct?
ANO is acting as a catalyst, but NO2 is not acting as a catalyst.
BNO2 is acting as a catalyst, but NO is not acting as a catalyst.
CNeither NO nor NO2 are acting as catalysts.
DBoth NO and NO2 are acting as catalysts.
✓ Correct Answer
The correct answer is D: Both NO and NO2 are acting as catalysts.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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