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Which O-Level Pure Chemistry topics come up most often?
We counted every question in 25 O-Level Pure Chemistry papers in Rae's library: 954 questions across 29 topics. The most common single topic is Ionic, covalent and metallic bonding, at 9.1% of all questions.
Every topic, ranked
| Topic | Questions | Share | Papers | Avg marks |
|---|---|---|---|---|
| Ionic, covalent and metallic bonding | 87 | 9.1% | 23 | 1.6 |
| Chromatography and melting/boiling point analysis | 68 | 7.1% | 16 | 1.2 |
| Formulae, equations and mole calculations | 60 | 6.3% | 23 | 1.4 |
| Acids, bases, pH and neutralisation | 56 | 5.9% | 16 | 1.3 |
| Kinetic theory of matter and diffusion | 52 | 5.5% | 21 | 1.4 |
| Lab techniques and purification methods | 49 | 5.1% | 15 | 1.3 |
| Qualitative tests for ions and gases | 47 | 4.9% | 16 | 1.5 |
| Periodic table trends and group properties | 46 | 4.8% | 18 | 1.8 |
| Atomic structure and isotopes | 45 | 4.7% | 16 | 1.2 |
| Structure-property relationships in materials | 45 | 4.7% | 18 | 2.0 |
| Rates of reaction and catalysis | 40 | 4.2% | 12 | 1.9 |
| Stoichiometry, yield and purity calculations | 34 | 3.6% | 12 | 1.6 |
| Electrolysis and electrochemical cells | 32 | 3.4% | 13 | 1.8 |
| Polymers, plastics and recycling | 32 | 3.4% | 10 | 1.4 |
| Metal reactivity, corrosion and extraction | 31 | 3.2% | 13 | 1.5 |
| Salt preparation and solubility rules | 31 | 3.2% | 11 | 1.5 |
| Alcohols, carboxylic acids and esters | 28 | 2.9% | 10 | 1.5 |
| Oxidation, reduction and redox reactions | 26 | 2.7% | 12 | 1.7 |
| Energy changes in reactions | 22 | 2.3% | 9 | 2.0 |
| Transition elements and reactivity series | 21 | 2.2% | 10 | 1.5 |
| Hydrocarbons: alkanes and alkenes | 18 | 1.9% | 9 | 1.3 |
| Practical experimental design and planning | 17 | 1.8% | 7 | 2.3 |
| Ammonia manufacture and reversible reactions | 15 | 1.6% | 7 | 1.2 |
| Data handling, measurement and evaluation skills | 12 | 1.3% | 6 | 1.4 |
| Crude oil, fuels and biofuels | 11 | 1.2% | 7 | 1.5 |
| Environmental issues: acid rain, ozone, greenhouse effect | 10 | 1.0% | 7 | 1.5 |
| Air composition and pollutants | 9 | 0.9% | 7 | 1.2 |
| Carbon cycle and climate impact | 5 | 0.5% | 4 | 1.4 |
| Fuel cells and electroplating | 5 | 0.5% | 4 | 1.0 |
How to use this
Topic frequency is a guide to where revision time pays back, not a prediction. The three topics that appear most here (Ionic, covalent and metallic bonding, Chromatography and melting/boiling point analysis, Formulae, equations and mole calculations) are worth being fluent in, but a topic near the bottom of the table can still carry a whole question in any given year.
Method, and what this is not
These counts come from real O-Level Pure Chemistry papers held in Rae's library (papers dated 2019 to 2025), which include school preliminary papers as well as national papers. Each question is labelled with one topic. This is a count of what our library contains, not an official SEAB distribution, and it does not tell you what will be set in a future exam. Questions that could not be labelled with a single topic are excluded from the counts.
You are welcome to cite or link to this page. If you would like the underlying counts in another format, get in touch through the O-Level Pure Chemistry page.