A-LevelChemistryAtoms, molecules and stoichiometryOct/Nov 2013Paper 1 Q81 Mark
Use of the Data Booklet is relevant to this question. The approximate percentage composition of the atmosphere on four different planets is given in the table below. The density of a gas may be defined as the mass of 1 dm³ of the gas measured at s.t.p. Which mixture of gases has the greatest density? [Table showing major gases/% by number of molecules for Jupiter, Neptune, Saturn, Uranus]
AJupiter H2 89.8, He 10.2
BNeptune H2 80.0, He 19.0, CH4 1.0
CSaturn H2 96.3, He 3.25, CH4 0.45
DUranus H2 82.5, He 15.2, CH4 2.3
✓ Correct Answer
The correct answer is D: Uranus H2 82.5, He 15.2, CH4 2.3
📋 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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