0620_m26_gt — 2026 March Chemistry 0620 Grade Threshold · Cambridge CAIE IGCSE

Giving conclusions instead of observations

“Candidates should understand what the word 'observations' means. 'A gas is produced' or to state the name of a product are not observations.”— Paper 4, May/June 2025

How to fix: When asked for observations, describe what you SEE or HEAR: effervescence/bubbling/fizzing (not 'gas produced'), colour changes (state from X to Y), solid dissolves/disappears, precipitate forms (white/cream/brown), temperature rises/falls. NEVER name a chemical product — 'hydrogen is produced' is a conclusion, not an observation.

Not reading the question stem carefully

“Candidates should take care to read each question carefully especially where chemical names are very similar such as ethane/ethene or chlorine/chloride.”— Paper 2, May/June 2025

How to fix: Before writing: (1) Underline the command word (state, explain, describe, suggest, deduce). (2) Check for 'other than' — don't repeat what's already given. (3) Check 'element' vs 'compound', 'name' vs 'formula', 'observation' vs 'conclusion'. (4) If the question says 'one reason', give exactly one — extra wrong answers cancel out correct ones.

Incomplete or incorrect definitions

“Many candidates could state part of the definition but not all of it. Most omitted the words 'compound' or 'only' which were needed to gain credit.”— Paper 3, May/June 2025

How to fix: Learn these definitions precisely: element, compound, mixture, alloy, hydrocarbon, homologous series, isotope, ion, catalyst, thermal decomposition, dynamic equilibrium, oxidation, reduction. For two-word terms, explain EACH word separately. Test yourself by writing definitions from memory and checking against the syllabus.