How to Get an A* in IGCSE Chemistry (0620): Moles, Equations & Every Mark

Chemistry (0620) is the A* that rewards precision. Most students know the reactions — but they lose the top grade on the details: a missing state symbol, an unbalanced equation, a mole calculation that rounded too early, or a chemical test written from memory but not quite in the examiner's words. This guide shows you exactly where those marks hide and how to bank them.

1. Tier check: you need Extended

2. What an A* in 0620 actually takes

The exact A* mark is set after each exam and moves with difficulty, but on Extended it usually lands around the low-to-mid 80s. You don't need perfection — you need to stop leaking the precision marks that keep strong students on an A.

3. The method: past papers, marked strictly

1. Practise by topic, then full papers
   Drill one topic's questions until the method is automatic, then sit whole Paper 2 & Paper 4 papers under timing.
2. Mark against the scheme — exactly
   Chemistry schemes are strict on equations, state symbols and wording. Award marks the way an examiner would, not generously.
3. Log every lost mark by type
   Knowledge gap, calculation slip, or a precision error (equation/state symbol/units)? For most A*-hopefuls it's the last one — and it's the fastest to fix.

4. The topics that decide an A* in 0620

5. Precision: state symbols, equations & the mole

For calculations — the classic A* separator:

• Show every step of a mole calculation — method marks are awarded even if the final number is wrong.
• Round only at the very end, to 3 significant figures unless told otherwise. Rounding mid-calculation loses accuracy marks.
• Watch the units — cm³ vs dm³, g vs mol. Unit slips are one of the most common ways to lose a correct answer.

6. Free marks: memorise the chemical tests

7. Don't skip the practical paper

Whether you sit Paper 5 (Practical Test) or Paper 6 (Alternative to Practical), the same skills repeat every session and are very winnable:

1. Readings & observations
   Recording measurements and colour/state changes precisely, with correct units.
2. Tables & graphs
   Sensible scales, accurate plotting, best-fit lines and reading off values.
3. Identifying substances
   Using the chemical-test results to deduce the ions present.
4. Errors & improvements
   Naming sources of error and sensible improvements — repeatable marks.

8. A focused 4-week 0620 plan

1. Week 1 · Diagnose
   One full Paper 4 under timed conditions. Mark it strictly and list every topic and precision error.
2. Week 2 · Topics + moles
   Attack weak topics and drill mole calculations and balanced equations until they're automatic.
3. Week 3 · Full papers + tests
   Timed Paper 2 + Paper 4, memorise the qualitative-analysis tests, and do a past Paper 5/6.
4. Week 4 · Polish
   Re-do your error-log questions, lock in definitions and state symbols. One final timed paper.

9. For students across the Middle East

• Board check: most Gulf schools sit Cambridge 0620; some sit Edexcel International GCSE Chemistry (graded 9–1). Revise from your board's papers.
• Practical route: many regional centres use Paper 6 (Alternative to Practical) — confirm yours and practise that exact paper.
• University: Chemistry is essential for medicine, pharmacy and engineering pathways in the region — a strong 0620 grade is worth prioritising.

FAQ

Chemistry rewards the precise. Get on the Extended tier, master moles and balanced equations, memorise the chemical tests, and practise the practical paper — do that and 0620 becomes one of your most reliable A*s.