The Most-Tested Topics in A-Level Chemistry (CIE 9701)
Every 9701 past-paper question, tagged to its syllabus topic — ranked by how often each is tested (2007–2024).
AS Level (Papers 1–3)
106 papers analysed · top 15 of 50 topics
| # | Topic | % of all questions | Questions | Avg marks |
|---|---|---|---|---|
| 1 | Reacting masses and volumes | 14.6% | 155 | 9.6 |
| 2 | Redox processes: electron transfer and oxidation number | 7.8% | 83 | 7.5 |
| 3 | Formulas and equations | 7.1% | 75 | 11.7 |
| 4 | Isomerism: structural and stereoisomerism (cis-trans) | 5.2% | 55 | 6.8 |
| 5 | Enthalpy change, delta H | 4.9% | 52 | 7.2 |
| 6 | Chemical equilibria, Kc and Kp | 4.7% | 50 | 5.3 |
| 7 | Reactions of the halide ions | 4.5% | 48 | 9.7 |
| 8 | Characteristic organic reactions (AS) | 4.4% | 47 | 10.6 |
| 9 | Aldehydes and ketones | 4.2% | 45 | 4 |
| 10 | Rate of reaction | 4.2% | 45 | 10.7 |
| 11 | Alkenes | 4.1% | 44 | 7.4 |
| 12 | Halogenoalkanes | 4.1% | 43 | 6 |
| 13 | The mole and the Avogadro constant | 4.1% | 43 | 10.8 |
| 14 | Bonding and structure (giant and simple) | 3.7% | 39 | 8.7 |
| 15 | Alcohols | 3.4% | 36 | 5.8 |
A Level (A2 topics) (Papers 4–5)
106 papers analysed · top 15 of 38 topics
| # | Topic | % of all questions | Questions | Avg marks |
|---|---|---|---|---|
| 1 | Characteristic chemical properties of transition elements (ligands, complexes, redox) | 3.7% | 39 | 11.8 |
| 2 | Acids and bases (Ka, pKa, Kw, pH, buffers, Ksp) | 2.6% | 28 | 14.4 |
| 3 | Standard electrode potentials, cell potentials and the Nernst equation | 2.4% | 25 | 13.4 |
| 4 | Organic synthesis (A Level) | 2.4% | 25 | 11.6 |
| 5 | Rate equations, orders of reaction and rate constants | 2.1% | 22 | 12 |
| 6 | Group 2 trends via energetics (thermal stability and solubility) | 2% | 21 | 13.4 |
| 7 | Stereoisomerism in transition element complexes | 2% | 21 | 12.2 |
| 8 | Arenes | 1.7% | 18 | 14.4 |
| 9 | Proton (1H) NMR spectroscopy | 1.7% | 18 | 13.1 |
| 10 | Lattice energy and Born-Haber cycles | 1.6% | 17 | 13.8 |
| 11 | Gibbs free energy change, delta G | 1.6% | 17 | 13.7 |
| 12 | Colour of complexes | 1.5% | 16 | 13.3 |
| 13 | Characteristic organic reactions (A Level) | 1.5% | 16 | 12.9 |
| 14 | Carbon-13 NMR spectroscopy | 1.4% | 15 | 12.5 |
| 15 | Entropy change, delta S | 1.2% | 13 | 13.8 |
How this was measured
Based on OwlsPrep's database of official CIE 9701 past papers (2007–2024), 1061 questions each tagged to its syllabus topic. “% of all questions” = the share of all tagged 9701 questions that test the topic. Because one question can test several topics, shares do not sum to 100%. AS and A2 are listed separately; A2 tends to use fewer, higher-mark questions. Figures are aggregate statistics from question metadata — no exam questions or mark schemes are reproduced.
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