If you are currently scoring under 25 out of 40 on IGCSE Chemistry Paper 2 (0620), you are not behind — you are at the starting line. The difference between students who plateau and students who break through is not intelligence. It is method. This guide lays out the exact four-stage preparation framework used by Hosni Showike, Head of Science at Nottingham British School in Kuwait and author of five published chemistry and biology textbooks, to take students from single-digit mistakes to near-perfect scores — sometimes in under two weeks.

What is IGCSE Chemistry Paper 2 and why do students struggle with it?

IGCSE Chemistry Paper 2 is a 45-minute multiple choice paper containing 40 questions, each worth one mark, covering both Core and Supplement content of the Cambridge 0620 syllabus. No calculator is permitted, which immediately makes non-calculator mole calculations — estimating percentage composition, working with molar masses like 40 for CaO and 18 for H₂O — a genuine skill that must be practised, not just understood. The paper is worth 30% of the total IGCSE Chemistry grade.

Students struggle because Paper 2 tests skills, not just recall. A student who can recite a definition may still answer incorrectly if they cannot apply it under time pressure. The questions follow the order of the syllabus, which is actually a strategic advantage most students never exploit: if you know where in the paper a topic sits, you already know where you will gain or lose time.

How do I know which topics I have forgotten before I start revising?

The fastest diagnostic tool available is a single past paper used as a gap finder, not a score. Before opening any revision notes, sit a full Paper 2 from any session between 2016 and 2020 under realistic conditions — quiet room, pencil, answer grid — and mark it honestly. Because IGCSE Chemistry past papers are arranged in syllabus order, clusters of wrong answers will map directly to the topics you have forgotten. Topic 3 (Stoichiometry) questions in the same section? That is your mole gap. Several wrong in the energetics cluster? That is your next target.

This diagnostic replaces two hours of aimless re-reading with a precise list of chapters that need attention. Do a fast read — not full memorisation — of only those chapters. You are not writing answers at this stage; you are reconnecting knowledge. Keep this phase short because time spent here is time not spent on the skill-building stages that follow.

What is the right order for practising past papers?

The staged progression below is the method that produced a 50%+ improvement for Hosni's student Hani, who moved from 22 out of 40 to scoring 39 and then a perfect 40 in the final week before his exam — a turnaround achieved in roughly two weeks.

Stage 1 — Open-notes practice (2016–2020)

Solve one variant per exam session from 2016 to 2020 with your notes fully open. The goal is not to test yourself; it is to reconnect exam questions to the knowledge in your notes. This rebuilds the mental links that time and stress have broken. Do not skip this stage because it feels like cheating — it is not. It is calibration.

Stage 2 — Closed practice with error logging (2020–2023)

Move to two variants per session from 2020 to 2023, this time checking answers only at the end of the full paper. Compile an error log — highlight mistakes and take screenshots to use as flashcards. This single habit dramatically reduces repeated errors because you are forced to confront the same mistake in a retrievable form, not just move past it. If the same topic appears in your error log three or more times, re-read that chapter before continuing.

Stage 3 — Timed practice (2023 onwards)

The 2023 syllabus revision introduced changes that affect question framing, so all papers from 2023 onwards should be treated as the highest-priority material. At this stage, time every paper. The target is to complete the full 40 questions within 45 minutes. For many students, time pressure — not knowledge gaps — is the primary cause of silly mistakes: confusing command words, forgetting to convert cm³ to dm³, selecting an answer without checking that it makes chemical sense.

Stage 4 — Full mock conditions (five final papers)

Sit five complete mocks from the most recent sessions using a soft pencil and the official Cambridge answer grid. You need the physical habit of filling in bubbles accurately under pressure — this is a separate skill from knowing the answer. Your target score at this stage is 36 out of 40.

Why is 36 out of 40 the right target score?

Scoring 36 out of 40 on Paper 2 is the safe-side target based on a statistical analysis of recent Cambridge grade boundaries. Across multiple recent exam sessions, the minimum mark for the top grade has averaged around 34 out of 40. Targeting 36 builds in a two-mark buffer for exam-day nerves, misreads, or a slightly harder variant — because variant difficulty does vary. A strong Paper 2 score also compensates for any marks dropped in Paper 4 (Theory) or Paper 6 (Practical), making it one of the highest-leverage papers to master before exam day.

Which topics in Paper 2 take too long and what should I do about them?

Two topic areas reliably drain time in Paper 2: mole calculations and energetics. Together, mole and energetics questions account for around three marks in every Paper 2 sitting — and they are the questions where students spend four to five minutes on a question worth exactly one mark. The strategic answer is to skip both topic clusters on a first pass and return to them at the end, after all faster questions are secured.

However, skipping is only a short-term tactic. The long-term solution is mastery. Two of Hosni's students — Lamar and Sama — chose to work through classified past paper questions on mole calculations and energetics exclusively, drilling only those two topics until the methods became automatic. Both entered the exam able to answer those questions in under 90 seconds. The most common errors in mole questions — using the wrong formula, forgetting to convert cm³ to dm³, omitting units — disappear with enough repetition of the correct method.

TopicAvg. time per question (unpractised)Avg. time per question (after classified practice)Marks at stakeMole calculations3–5 minUnder 90 sec~2 per paperEnergetics (ΔH)2–4 minUnder 60 sec~1 per paperAll other topicsUnder 60 secUnder 45 sec~37 per paper

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How many mistakes is it normal to make right now?

Getting more than 10 mistakes on a Paper 2 practice exam right now is completely normal, particularly if your last chemistry exam was two or more weeks ago. Mole calculations are the most frequently failed topic at this level, and forgetting details between exam sessions is not a sign of weakness — it is how memory works without active retrieval practice. What matters is the trajectory, not the starting point. Hani began with 22 out of 40. What changed was not his intelligence; it was the method and the two weeks he committed to it.

What is not normal — and what requires immediate action — is scoring the same mark across multiple practice papers without improvement. That signals a strategy problem, not a knowledge problem. The staged method above is designed specifically to break that plateau.

FAQ

1. Can I prepare for IGCSE Chemistry Paper 2 in two weeks? Yes — two weeks is sufficient time to move from a failing score to a near-perfect one, provided you follow a structured four-stage progression rather than passive re-reading. Hani's improvement from 22 to 40 out of 40 happened in this window using the method described above.
2. Should I revise all topics before practising past papers? No. Use one diagnostic past paper first to identify exactly which topics you have forgotten, then do a fast targeted read of only those chapters. Revising everything wastes time that should be spent on skill-building practice.
3. Is it better to check answers after each question or at the end of the paper? At the end of the paper, always. Checking after each question breaks your exam rhythm and prevents you from experiencing genuine time pressure, which is a core Paper 2 skill in itself.
4. What score should I aim for in Paper 2 practice before the real exam? Target 36 out of 40 consistently across your final five timed mocks. This sits above the statistically observed grade boundary average of around 34 and gives you a two-mark buffer for exam-day variation.

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