IGCSE Chemistry exam technique 2026: The complete guide to scoring higher marks

IGCSE Chemistry exam technique is about turning subject knowledge into precise, mark-scheme-friendly answers under exam conditions. To score well, students need to read command words carefully, structure explanations clearly, show full working in calculations, write accurate chemical equations, and manage their time effectively. Strong exam technique also involves interpreting unfamiliar data, separating observations from conclusions, and checking common errors before submitting the paper.

This guide covers the key strategies students can use across Paper 2, Paper 4, and Paper 6 to improve consistency and maximise marks.

IGCSE Chemistry exam technique for higher marks

The single biggest gap between students who score in the top band and those who plateau in the mid-range is not knowledge. It is exam technique. A student who understands particle theory but writes a vague answer will lose marks to a student who knows slightly less but writes with precision.

Cambridge IGCSE Chemistry 0620 ^[1] uses three assessment objectives: AO1 (Knowledge and Understanding), AO2 (Application), and AO3 (Analysis, Interpretation, and Evaluation). Most students are reasonably prepared for AO1 questions, but it is the AO2 and AO3 questions that separate the grades. Mastering exam technique means learning how to perform on all three levels, not just recall.

The techniques in this guide are built around the exact expectations of Cambridge International mark schemes and examiner reports, so every recommendation is grounded in what actually earns marks.

>>> Read more: IGCSE Chemistry 0620 books 2026: Complete guide for students and teachers

How to approach each IGCSE Chemistry exam paper

Each paper in IGCSE Chemistry 0620 has a distinct structure and demands a different tactical approach.

For Paper 4, read the entire question before writing a single word. Many students answer the first sub-part without noticing that a later sub-part gives them a hint or contradicts an assumption they made early on.

For Paper 6, treat every question as having two layers: What happened in the experiment (observation) and why it happened (conclusion). Examiners consistently reward students who separate these two layers cleanly.

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How to read command words correctly in Chemistry questions

Command words are the single most reliable guide to what an examiner expects in your answer. A common mistake we see at Times Edu is students writing long explanations when the question says “state,” wasting time and earning no extra marks.

Cambridge International publishes an official command word glossary, and every IGCSE Chemistry student must know it. The table below covers the most frequently tested command words and what each one requires.

One critical detail often overlooked is that “describe” and “explain” are frequently combined in the same question. When a question says “Describe and explain,” you must do both. Writing only a description will earn you half the marks at most.

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How to structure state, describe and explain answers

The three most common command words in IGCSE Chemistry theory papers are “state,” “describe,” and “explain.” Each one has a distinct structure that you should practise until it becomes automatic.

For “state” questions, your answer should be one or two words or a single clause. Do not add “because” or “this is due to.” The examiner is not rewarding your reasoning here, only your recall.

For “describe” questions, use a sequential structure. If you are describing what happens when sodium reacts with water, list the observable steps: The sodium floats, it moves rapidly across the surface, a colourless gas is produced, the metal eventually disappears. No causes, no reasons.

For “explain” questions, the mark scheme almost always requires a specific chemical cause. In our experience working with international students, the most reliable structure is: State the observation, then write “this is because” followed by the chemical reason. For example: “The solution turns blue because copper(II) ions are present, which form a deep blue complex with excess ammonia.”

>>> Read more: IGCSE Chemistry Mark Scheme Keywords for 2026: The Terms You Need to Use for Better Marks

How to answer suggest and predict questions

“Suggest” and “predict” questions belong to AO2 and AO3, meaning they test your ability to apply chemistry to situations you have not directly studied. These are the questions that genuinely separate Grade 7 from Grade 9 candidates.

For “suggest” questions, examiners are looking for scientific logic, not a memorised answer. Ask yourself which chemical concept from the syllabus is being triggered by the question. If the question shows an unfamiliar compound with a high melting point and asks you to suggest its bonding, you apply your knowledge of giant ionic or covalent structures to reach a reasoned answer.

For “predict” questions, always anchor your answer to a known trend or pattern. Periodic table trends, reactivity series positions, and electronegativity patterns are the most commonly used frameworks. State the trend explicitly before giving your prediction, as this shows the examiner your reasoning pathway even if your final answer is slightly off.

>>> Read more: IGCSE Chemistry 0620 Command Words: Decode Exam Questions for A*

How to show working in Chemistry calculations

Calculation questions in IGCSE Chemistry, particularly mole calculations, titration calculations, and percentage yield questions, follow a strict marking structure. Each step of the working is a potential mark, and examiners are trained to award marks for correct method even when the final numerical answer is wrong.

The correct approach follows four non-negotiable steps:

1. Write the formula or equation you are using before substituting any numbers.
2. Substitute the values with their units clearly shown.
3. Carry the unrounded value through every step of a multi-step calculation.
4. Round only your final answer, to three significant figures unless the question specifies otherwise.

A common mistake we see is students writing only the final answer for a three-mark calculation question. Even if that answer is correct, they earn one mark. If it is slightly wrong due to a rounding error mid-calculation, they earn zero. Always show every step.

Units are also a marks-carrying component. An answer of “0.25” with no unit attached will not earn the unit mark. Write “0.25 mol” or “0.25 g” every time.

>>> Read more: IGCSE Chemistry 0620 Topic Order: Best Sequence for A* Revision

How to answer chemical equation questions accurately

Writing chemical equations correctly is a discipline that requires practice and a systematic checking process. Cambridge IGCSE Chemistry 0620 tests word equations, symbol equations, ionic equations, and half-equations across Papers 2 and 4.

For symbol equations, check three things before moving on: The formulae of each substance are correct, the equation is balanced in terms of atom count, and state symbols are included if the question asks for them. State symbols (s), (l), (g), and (aq) are frequently worth one mark and are just as frequently left out.

For ionic equations, you must cancel spectator ions. A common thinking trap is writing the full equation and assuming it qualifies as ionic. It does not. Identify the ions that do not change between reactants and products, remove them from both sides, and check that charge is balanced across the ionic equation.

One critical detail often overlooked is that ionic equations must also balance for charge, not just atoms. Check that the total charge on the left side equals the total charge on the right side before finalising your answer.

>>> Read more: IGCSE Chemistry Past Paper Strategy for 2026: Smart Ways to Practice for Better Results

How to approach observation and qualitative analysis questions

Qualitative analysis questions appear most heavily in Paper 6 but also feature in Paper 4 theory questions. The key skill is separating observation from conclusion, two layers that many students incorrectly blend.

An observation is what you directly see, hear, or detect: A colour change, a precipitate forming, a gas being produced. A conclusion is the chemical interpretation: What ion or compound that observation indicates. Never write “iron(III) ions are present” as an observation. Write “a red-brown precipitate forms” as the observation, then “this indicates the presence of iron(III) ions” as the conclusion.

For gas tests, always write both the test reagent and the positive result. Stating “test with damp red litmus paper” is incomplete without “which turns blue, indicating ammonia.” Mark schemes consistently require both components. Commit the full test-and-result pairs for ammonia, hydrogen, oxygen, carbon dioxide, and chlorine to memory.

How to answer particle-level explanation questions

The particle model is central to IGCSE Chemistry, and particle-level explanation questions test your ability to reason at the submicroscopic scale. These questions frequently appear in sections on bonding, states of matter, reaction rates, and energy changes.

When answering particle-level questions, always name the specific particles involved. “Particles move faster” is a weaker answer than “water molecules move faster.” “The bond breaks” is weaker than “the covalent bond between the two carbon atoms breaks.” Specificity is the difference between one mark and two marks.

In our experience working with international students who are strong in general science but new to Cambridge-style chemistry, the most common error is explaining in terms of macroscopic properties rather than particles. If the question asks why a solid dissolves faster when crushed, the answer must reference increased surface area exposing more particles to contact with solvent molecules, not simply “more surface area means faster dissolving.”

How to tackle unfamiliar data and application questions

AO3 questions present data you have never seen before and ask you to interpret it. These questions reward students who can read a graph, a table, or a passage carefully and extract the precise information the question is asking about.

The most effective strategy is to read the data source before reading the question. Spend 20 to 30 seconds understanding what the axes, units, and trends show before committing to an answer. Students who jump to the question first frequently misread the scale or miss a turning point in a graph.

When asked to draw a conclusion from data, use comparative language anchored to specific values. Do not write “the rate increases as temperature increases.” Write “the rate doubles from 20 cm³/min to 40 cm³/min as temperature rises from 20°C to 40°C, suggesting a direct proportional relationship in this range.” The specificity of your evidence is what converts a one-mark answer into a two-mark answer.

How to manage time in the IGCSE Chemistry exam

Time management is an underrated component of Chemistry exam strategy. Paper 4, for instance, carries 80 marks in approximately 75 minutes, meaning you have roughly one minute per mark. This is a tight window that rewards disciplined pacing.

Allocate time at the start of the exam to skim the entire paper and identify which questions you will complete quickly and which need more thought. Do not spend five minutes on a two-mark question when a six-mark question later in the paper is waiting.

If you are stuck on a question, write your best attempt, circle it, and move on. Return with fresh eyes in the last ten minutes. A blank answer earns zero marks; a partial answer can still earn one or two marks for correct elements of the response.

How to use past papers and mark schemes effectively

Past papers and mark schemes are the most powerful revision tools available for IGCSE Chemistry 0620, but only when used correctly. A common mistake we see is students completing a past paper and simply checking which answers were right or wrong without understanding why.

The correct process is: Complete the paper under timed conditions, self-mark using the official mark scheme, and then read the examiner report for that session. Examiner reports explicitly state the most common errors, the phrases that earned marks, and the misconceptions that cost candidates marks. This is free, official guidance that most students ignore entirely.

Build an error log after every past paper session. Record the question type, the command word, the topic, and the specific reason you lost the mark. After five past papers, patterns will emerge that tell you exactly where your exam technique is weakest, allowing you to direct your revision with precision rather than reviewing everything equally.

Common exam technique mistakes that lose Chemistry marks

Drawing on years of experience at Times Edu reviewing student scripts and examiner reports, the following mistakes are the most consistent mark-losers across all IGCSE Chemistry papers.

• Writing “free electrons” instead of “delocalized electrons” in metallic bonding questions
• Omitting state symbols in equation questions that explicitly request them
• Confusing “describe” with “explain” and providing reasons when only observations are needed
• Rounding mid-calculation and carrying a rounded value into the next step
• Writing “iron” instead of “iron(II) ion” or “iron(III) ion” in qualitative analysis answers
• Using the word “amount” without specifying whether you mean mass, moles, or concentration
• Answering “compare” questions with only differences and no similarities
• Forgetting to balance charge when writing ionic equations

Each of these errors appears in examiner reports year after year. They are not knowledge gaps; they are technique gaps that targeted practice can correct within a few weeks.

How to check your answers before the exam ends

Reserve the final eight to ten minutes of every exam for systematic checking. Do not use this time to re-read every answer. Use a targeted checklist focused on the highest-probability errors.

Work through this checklist in the final minutes:

1. Check every calculation for units on the final answer.
2. Check every equation for state symbols if the question requested them.
3. Check every ionic equation for charge balance.
4. Verify that “describe” answers contain no reasons and “explain” answers contain specific chemical causes.
5. Confirm that “compare” answers address both similarities and differences.
6. Check that significant figures on final numerical answers match the data given in the question.

Do not change answers based on gut feeling alone. Only revise an answer if you have identified a specific error, such as a miscalculation or a misread command word.

Frequently asked questions

How can I improve my IGCSE Chemistry exam technique?

The fastest route to improvement is completing past papers under timed conditions, self-marking with official mark schemes, and reading the corresponding examiner reports. After each session, build an error log that tracks which command words and question types are consistently costing you marks. Target those specific areas in your next revision session rather than reviewing the entire syllabus.

How do you score high marks in IGCSE Chemistry?

High marks come from combining strong content knowledge with precise exam technique. Use correct chemical terminology, show all working in calculations, include state symbols in equations, and always respond to the specific command word in the question. Students who consistently hit Grade 8 and 9 at Times Edu are those who practise technique as deliberately as they practise content.

How should I answer explain questions in IGCSE Chemistry?

Structure your answer as: Observation plus chemical cause. Write what happens first, then write “this is because” followed by the specific chemical reason. Use precise scientific vocabulary, name the particles involved, and avoid vague phrases like “it reacts faster” without specifying the mechanism.

How do you avoid careless mistakes in Chemistry exams?

Careless mistakes are reduced through a consistent checking routine. Reserve the last eight to ten minutes for a targeted review of units, state symbols, charge balance in ionic equations, and significant figures. Build this habit in every past paper session so it becomes automatic in the actual exam.

Should you show all working in IGCSE Chemistry calculations?

Yes, without exception. Cambridge mark schemes award marks for each correct step of a multi-step calculation independently. Showing your working means you can earn partial marks even if your final answer is wrong. Writing only the final answer risks earning zero if that answer contains even a minor error.

How many past papers should I do for IGCSE Chemistry?

Aim for a minimum of eight to ten complete past papers under timed, exam-like conditions. Quality of review matters as much as quantity: Each paper must be followed by thorough mark scheme analysis and error logging. Cambridge International releases papers from 2017 onwards for Chemistry 0620, giving you ample material for a structured revision programme.

What should I check at the end of an IGCSE Chemistry exam?

Focus your final check on the six highest-probability errors: Missing units on calculation answers, absent state symbols in equations, unbalanced charge in ionic equations, misapplied command words, incomplete “compare” answers, and incorrect significant figures. Avoid re-reading essay-style answers unless you have specific reason to believe something is wrong.

Cao Linh