A-LevelChemistryAtoms, molecules and stoichiometryFeb/Mar 2025Paper 1 Q251 Mark
Two nitrates decompose on heating according to the equations shown. 2Pb(NO3)2(s) → 2PbO(s) + 4NO2(g) + O2(g) 2NH4NO3(s) → 2N2(g) + O2(g) + 4H2O(l) One mole of each nitrate is heated separately. The gas produced in each reaction is bubbled through NaOH(aq). The volume of any gas that does not react with NaOH(aq) is then collected and measured. Which nitrate: • shows the greater percentage loss in mass • produces the greater volume of gas collected?
ANH4NO3 NH4NO3
BNH4NO3 Pb(NO3)2
CPb(NO3)2 NH4NO3
DPb(NO3)2 Pb(NO3)2
✓ Correct Answer
The correct answer is A: NH4NO3 NH4NO3
📋 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.
🔒
Unlock the Examiner's Analysis
Sign up for free to reveal the full examiner report, trap analysis, and mark scheme breakdown for this question.
Sign Up Free to Unlock →Join thousands of Cambridge students already using Oracle Prep