IGCSE Chemistry how to get full marks in the exam 2026
To get full marks in IGCSE Chemistry, students need more than strong subject knowledge—they must answer with the precision, structure, and scientific language the Cambridge mark scheme expects. This means interpreting command words correctly, showing complete working in calculations, writing accurate equations, and building clear cause-and-effect explanations. Strong practical skills, careful use of mark schemes and examiner reports, and targeted past-paper practice are equally important. This guide explains the key strategies students can use to reduce avoidable errors and maximise marks across Cambridge IGCSE Chemistry 0620.
- What full-mark Chemistry answers need to include
- Know the syllabus before starting intensive revision
- Use command words to understand exactly what the question requires
- Use precise scientific terminology in every answer
- How to get full marks in Chemistry calculations
- How to write balanced chemical and ionic equations accurately
- How to score full marks in explain questions
- How to master qualitative analysis questions
- How to score highly on practical and Alternative to Practical questions
- How to use mark schemes to identify missing marking points
- How examiner reports reveal common lost marks
- How to use past papers to improve accuracy and speed
- How to build an error log for recurring Chemistry mistakes
- How to check your Chemistry paper before submitting it
- Frequently asked questions
What full-mark Chemistry answers need to include
A full-mark answer in Cambridge IGCSE Chemistry [1] requires three things working together: Correct chemical content, precise scientific language, and a structure that matches the mark scheme points one for one.
Examiners mark against a detailed mark scheme. Each marking point is worth exactly one mark, and your answer must hit that specific point to earn it. A response can contain accurate chemistry and still score zero if it uses vague language, omits a key term, or misunderstands what the command word is asking.
The three Assessment Objectives (AO1, AO2, AO3) define what type of thinking each question tests. AO1 is recall of knowledge, AO2 is application and analysis, and AO3 is experimental and investigative skills. A full-mark strategy must address all three categories, not just content memorization.
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Know the syllabus before starting intensive revision
One critical detail often overlooked is that students start revising without first reading the Cambridge IGCSE Chemistry 0620 syllabus document in full. The syllabus tells you exactly which topics are assessed, what depth of knowledge is required, and whether a topic is Core Chemistry only or also tested at Extended Chemistry level.
Extended Chemistry students sitting Paper 2 and Paper 4 must cover additional content including moles, stoichiometry, and more detailed explanations of bonding and structure. Core Chemistry students do not need to master all of this, but many students waste revision time on the wrong tier.
Before building your revision plan, download the current syllabus from the Cambridge International website and tick off every topic. Use the syllabus as your master checklist, not a textbook chapter list, because not every chapter in a textbook maps exactly to what is examined.
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Use command words to understand exactly what the question requires
A common mistake we see at Times Edu is students treating “state,” “explain,” and “describe” as interchangeable. They are not, and confusing them is one of the most reliable ways to drop marks on questions you actually know the answer to.
| Command word | What it requires | Common mistake |
|---|---|---|
| State | Give a single fact, no explanation needed | Writing a full paragraph when one word suffices |
| Describe | Say what happens, including observations | Explaining why instead of what |
| Explain | Give the reason using chemical logic | Stating a fact without linking it to a cause |
| Suggest | Apply knowledge to an unfamiliar context | Leaving it blank because it looks unknown |
| Calculate | Show working and give a numerical answer with units | Giving only the final answer with no method |
| Deduce | Draw a conclusion from given data | Restating the data without drawing a conclusion |
Reading the command word first, before reading the rest of the question, trains you to frame your answer correctly from the first sentence. This single habit alone has helped many of our students pick up an extra four to six marks per paper.
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Use precise scientific terminology in every answer
Chemistry exam tips from Cambridge examiner reports consistently flag the same language errors year after year. Eliminating these errors is the fastest way to improve your Chemistry A* strategy.
Never write “clear” to describe a colorless liquid. Clear means you can see through something. Copper sulfate solution is blue and clear. If a liquid has no color, write “colorless.” This distinction costs students marks every single exam session.
Never use “it” or “they” without a named subject. If asked why graphite conducts electricity, do not write “because it has free electrons.” Write “because graphite has delocalized electrons that are free to move and carry charge.” The named subject and the complete chemical reason are both required.
Never say “bonds break” when describing the melting or boiling of simple molecular substances. When iodine sublimes or water boils, the covalent bonds within the molecules do not break. Only the weak intermolecular forces (van der Waals forces or hydrogen bonds) overcome. Writing “bonds break” is chemically incorrect and will not earn the mark.
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How to get full marks in Chemistry calculations
Calculations appear throughout Paper 2 and Paper 4, and they follow predictable patterns. In our experience working with international students, the most reliable method for maximizing marks is what we call the N.M.R. Layout: Number of moles, Molar ratio, Rearrange.
Step 1: N (Number of moles). Calculate the moles of the substance for which you have data. Use Moles = Mass / Mr, or Moles = Volume (dm³) × Concentration (mol/dm³).
Step 2: M (Molar ratio). Write the balanced equation and identify the ratio between the substance you calculated and the substance you need to find. Apply that ratio to find the moles of the unknown.
Step 3: R (Rearrange). Convert the moles of the unknown into the final unit the question requests: Mass, volume, or concentration.
One critical detail that separates full-mark answers from near-misses: Never round numbers mid-calculation. Keep the full decimal on your calculator and round only the final answer to three significant figures unless the question specifies otherwise. Rounding mid-way introduces compounding errors that can cost you the final mark even when all your chemistry logic is correct.
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How to write balanced chemical and ionic equations accurately
Balancing equations and writing ionic equations are high-value skills that appear across multiple question types in Cambridge IGCSE Chemistry 0620. A common mistake we see is students who know the reactants and products but lose marks by forgetting state symbols or failing to cancel spectator ions correctly.
For balanced chemical equations, always check three things: The chemical formulae are correct, the equation is balanced by atom count, and state symbols (s), (l), (g), and (aq) are included when the question asks for them.
For ionic equations, the method is: Write the full balanced equation, replace all soluble ionic compounds with their separate ions, then cancel any ion that appears identically on both sides of the equation. What remains is the net ionic equation. A student who writes the full equation but does not cancel spectator ions will lose the mark for the ionic equation even if the chemistry is correct.
How to score full marks in explain questions
Explain questions are the most mark-rich question type in Paper 4, and they require a chain of chemical reasoning, not just a single fact. The number of marks tells you precisely how many distinct chemical points you must include.
- A 2-mark explain question needs: One chemical fact plus one logical cause.
- A 3-mark explain question needs: One fact, one cause, and one consequence or further development.
- A 4-mark explain question typically requires two complete fact-cause pairs.
If a question gives you four blank lines, a single sentence will almost never earn full marks. Use the line count as a signal to expand your reasoning chain. Each sentence should introduce a new chemical idea that advances the explanation, not repeat the same point in different words.
How to master qualitative analysis questions
Qualitative analysis is tested directly in Paper 6 (Alternative to Practical) and indirectly in Paper 2 and Paper 4 through data-response questions. The skill being assessed is knowing both the test method and the specific expected observation.
A student who writes “add sodium hydroxide solution to test for metal ions” earns partial credit at best. A full-mark answer names the reagent, describes the exact observation, and links it to a named conclusion. For example: “Add sodium hydroxide solution dropwise; a blue precipitate forms, indicating the presence of copper(II) ions.”
| Ion tested | Reagent | Positive result |
|---|---|---|
| Cu²⁺ | NaOH(aq) | Blue precipitate forms |
| Fe²⁺ | NaOH(aq) | Green precipitate forms |
| Fe³⁺ | NaOH(aq) | Red-brown precipitate forms |
| NH₄⁺ | NaOH(aq), warm | Ammonia gas produced, turns moist red litmus blue |
| Cl⁻ | HNO₃(aq), then AgNO₃(aq) | White precipitate, insoluble in dilute HNO₃ |
| SO₄²⁻ | HCl(aq), then BaCl₂(aq) | White precipitate forms |
| CO₃²⁻ | Dilute HCl | Effervescence, gas turns limewater milky |
Memorizing this table is not enough. Practicing writing each test as a complete sentence, including the exact observation, trains the muscle memory needed under timed exam conditions.
How to score highly on practical and Alternative to Practical questions
Paper 6 tests practical skills through written questions rather than a live experiment, which means it rewards students who know the standard formula for answering each question type. In our experience working with international students, Paper 6 is the highest-return paper to prepare specifically, because the question formats repeat across sessions.
For a 6-mark planning question, always use these four headings:
- Apparatus: List every piece of equipment needed, including quantities (for example, “a 50 cm³ burette, not just “a burette”).
- Variables: Name the independent variable, the dependent variable, and at least two controlled variables.
- Method: Write a numbered step-by-step procedure including specific volumes, masses, and time intervals.
- Processing results: Explain how you will use the collected data, for example, “Plot a graph of volume of gas collected (y-axis) against time in seconds (x-axis).”
For gas tests, you must always write both the test and the positive result as a paired answer. Writing “use a glowing splint” earns zero marks. Writing “insert a glowing splint into the gas; it relights if oxygen is present” earns the full mark.
How to use mark schemes to identify missing marking points
Mark schemes are not answer keys to be memorized. They are diagnostic tools that reveal exactly which chemical points you are missing and why. Drawing on years of experience at Times Edu, we advise students to mark their own past paper answers against the mark scheme point by point, not holistically.
After attempting a question, highlight every mark scheme point in a different color: Green if you wrote it, red if you missed it, and orange if you wrote something partially correct. This granular analysis shows patterns. If you repeatedly miss the “free to move” phrase in conductivity explanations or forget state symbols in equations, that is the gap you address in your next revision session.
Never look at the mark scheme before attempting the question. The cognitive effort of trying to recall and construct an answer, even if imperfect, builds the active recall pathways that make knowledge stick during spaced repetition revision cycles.
How examiner reports reveal common lost marks
Cambridge International publishes examiner reports after every exam session. These reports describe the most common errors made by real students and often include verbatim examples of zero-mark answers alongside the correct phrasing. They are among the most underused revision resources available.
A common mistake we see is students who practice dozens of past papers but never read a single examiner report. The reports tell you what the examiners were looking for beyond what the mark scheme states, including acceptable alternative answers and the specific phrasing that earns no credit.
Focus particularly on the examiner report comments for questions in the topics where you score below 70%. Cross-reference those comments with your error log (covered in the next section) to build a targeted picture of exactly where your mark loss is concentrated.
How to use past papers to improve accuracy and speed
Past papers are the single most effective revision tool for Cambridge IGCSE Chemistry 0620, but only when used with the right method. Doing past papers passively (reading through and thinking “yes, I know that”) does not build exam skill. Doing them under timed, exam-condition pressure does.
For each past paper session:
- Set a timer to the exact paper length.
- Write answers by hand, not typed, since writing activates different memory retrieval pathways.
- Do not refer to notes or your textbook during the attempt.
- Mark immediately after using the official mark scheme.
- Record every missed mark in your error log before moving to the next paper.
Aim to complete at least eight to ten past papers across Paper 2, Paper 4, and Paper 6 in the final six weeks before your exam. Prioritize papers from the last four to five years, since these reflect the current syllabus and question style most accurately.
How to build an error log for recurring Chemistry mistakes
An error log is a running document where you record every mark you lost, the reason you lost it, and the corrected answer. It is a core part of any serious Chemistry A* strategy because it turns random mistakes into a structured revision target list.
A simple error log format works best:
| Date | Paper & question | Topic | Mark lost | My answer | Correct answer | Root cause |
|---|---|---|---|---|---|---|
| Example | Paper 4 Q3b | Moles | 1 | Rounded mid-calculation | Keep full decimal | Calculator habit |
| Example | Paper 6 Q2 | Gas test | 1 | Named test only | Named test + result | Incomplete answer format |
Review your error log every two weeks. Any error that appears three or more times is a priority target for active recall practice. Write the correct answer from memory without looking at your notes, then check it. Repeat until the correct phrasing comes automatically.
How to check your Chemistry paper before submitting it
The final five minutes of an IGCSE Chemistry paper are as valuable as the first five. A structured checking routine can recover two to four marks that were lost to careless errors, incomplete answers, or missing units.
Run through this checklist before submitting:
- Check that every calculation answer has the correct unit (g, mol/dm³, cm³, kJ/mol).
- Check that balanced equations include state symbols where required.
- Check that every “explain” answer has a cause linked to a consequence, not just a statement.
- Check that qualitative analysis answers include both the test and the specific observation.
- Check that any blank answer lines have at least an attempt written, since a blank line earns zero but a partial answer may earn one mark.
Never erase an answer completely unless you are certain it is wrong. Cross it out neatly and write the revised answer alongside it. Examiners mark what is written, and a partially correct crossed-out answer may still earn credit in some question types.
Frequently asked questions
How do you get full marks in IGCSE Chemistry?
Getting full marks requires combining accurate chemistry knowledge with precise scientific language, correct use of command words, and a structured approach to calculations, equations, and explain questions. Using mark schemes and examiner reports to identify specific gaps is essential, not optional.
How can I get an A* in IGCSE Chemistry?
An A* in Cambridge IGCSE Chemistry 0620 requires a raw mark that typically falls in the top 10% of the Extended tier cohort. To achieve this, students need to score heavily on Paper 4 (the structured Extended paper) and Paper 6 (Alternative to Practical), minimize mark loss on language errors, and demonstrate clear chemical reasoning in all explain questions.
What are the hardest topics in IGCSE Chemistry?
Based on examiner reports and performance data, the topics that cause the most mark loss are: Moles and stoichiometry calculations, ionic equations and balancing, electrochemistry, and organic chemistry reaction types. These topics are all high-yield areas that reward structured, repeated practice.
How many past papers should I do for IGCSE Chemistry?
A minimum of eight to ten full past papers under exam conditions is recommended in the final six weeks. Quality of review matters more than quantity: Each paper must be marked against the official mark scheme and all errors logged immediately.
How do you avoid losing easy marks in IGCSE Chemistry?
The most common easy-mark losses come from using “clear” instead of “colorless,” writing “bonds break” for simple molecular substances, giving incomplete gas test answers, omitting units in calculations, and using “it” or “they” without a named chemical subject. Eliminating these five habits alone can recover three to five marks per paper.
How should I use mark schemes when revising Chemistry?
Attempt every question fully before consulting the mark scheme. Then mark your answer point by point in different colors for correct, partially correct, and missed marks. Use the pattern of missed marks to build your error log and direct your next revision session.
What should I revise before an IGCSE Chemistry exam?
In the 48 hours before the exam, prioritize reviewing your error log, key definitions word-for-word, the qualitative analysis table, gas tests, the N.M.R. Calculation layout, and the command word table. Do not try to learn new content at this stage. Consolidate what you already know and sharpen your exam technique.
Conclusion
At Times Edu, our 1-on-1 IGCSE tutoring programs are built around exactly this approach: Identifying each student’s specific mark-loss patterns, closing content gaps at the Extended Chemistry level, and drilling exam technique until precise, examiner-ready answers become automatic. If you or your child is preparing for Cambridge IGCSE Chemistry 0620 and wants a personalized academic roadmap that targets the A*, our team is ready to build that plan with you.
