0620_m26_ci_52 — 2026 March Chemistry 0620 Confidential Instructions 5 Variant 2 · 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.

Poor recall of qualitative tests (ion tests, gas tests, indicator colours)

“Answering of chemical test questions was poorly done, showing large gaps in the knowledge of many candidates.”— Paper 3, May/June 2023

How to fix: Make flashcards for: (1) Gas tests — hydrogen (squeaky pop), oxygen (relights splint), CO₂ (white precipitate with limewater), ammonia (damp red litmus turns blue), chlorine (damp blue litmus turns red then bleaches white). (2) Ion tests — chloride/bromide/iodide with acidified silver nitrate (white/cream/yellow precipitate), sulfate with acidified barium chloride (white precipitate). (3) Flame test colours — Li=red, Na=yellow, K=lilac, Ca=orange-red, Cu=blue-green. (4) Indicator colours — methyl orange: red in acid, yellow in alkali; phenolphthalein: colourless in acid, pink in alkali.