How IGCSE Chemistry 0620 Is Marked: Papers and Lost Marks

Cambridge IGCSE Chemistry (syllabus code 0620) is taught in international schools around the world, including across the UAE and the Gulf. It rewards the same thing every chemistry exam rewards — precision — but the way the papers are built, and the choice between Core and Extended, shape where your marks come from. If you know how the exam is put together and where marks usually slip away, you can aim your revision at the marks that are actually available.

Everything below is taken from the Cambridge IGCSE Chemistry 0620 syllabus for exams in 2026, 2027 and 2028. Always check the syllabus for your own exam year on the Cambridge website, as details can change.

Three papers, not one

Every candidate sits three components: a multiple-choice paper, a theory paper and a practical paper. Which multiple-choice and theory papers you sit depends on whether you are entered for Core or Extended.

• Core: Paper 1 (Multiple Choice) and Paper 3 (Theory), plus a practical paper. Questions are based on the Core subject content only, and Core candidates are eligible for grades C to G.
• Extended: Paper 2 (Multiple Choice) and Paper 4 (Theory), plus a practical paper. Questions are based on the Core and Supplement content, and Extended candidates are eligible for grades A* to G.

The point that matters most here is the grade ceiling. A Core entry cannot achieve higher than a C, however well the student performs. If you are aiming for an A or A*, you need to be entered for Extended, which means revising the Supplement content as well as the Core. Check your entry with your teacher well before the exam.

Multiple choice: Paper 1 or Paper 2

The multiple-choice papers are 45 minutes long and contain 40 four-option questions, for 40 marks. They carry 30% of the qualification. That is a little over a minute per question, so speed matters, but the bigger risk is the distractor: the wrong options are written to catch common misconceptions. A student who half-remembers that “ionic compounds conduct electricity” will be caught by an option about solid ionic compounds. Read every option before choosing, and treat each one as a statement to test against what you know.

Theory: Paper 3 or Paper 4

The theory papers are where most of your marks are decided. Each lasts 1 hour 15 minutes, is worth 80 marks and carries 50% of the qualification. They are made up of short-answer and structured questions — a scenario or set of data followed by a series of parts that build on each other. This is where precise wording, equations and calculations are tested, and where the mark scheme’s exact requirements matter most. If you have not looked closely at how a mark scheme works, start there.

Practical: Paper 5 or Paper 6

Every candidate also takes one practical paper, worth 40 marks and 20% of the qualification. There are two options, and you take one:

• Paper 5, Practical Test (1 hour 15 minutes): you carry out experiments in a laboratory as part of the exam.
• Paper 6, Alternative to Practical (1 hour): you answer written questions about experiments without doing them.

Both test the same experimental skills — planning, observing, recording, interpreting and evaluating — and notes for qualitative analysis (the tests for ions and gases) are provided in both. Students sometimes treat the Alternative to Practical as a light paper because there is no lab work. It is not: it rewards students who have genuinely done the practicals and can picture the apparatus, the readings and what goes wrong.

What is being assessed

Cambridge weights the qualification across three assessment objectives: knowledge with understanding (50%), handling information and problem-solving (30%), and experimental skills and investigations (20%). The theory and multiple-choice papers test the first two; the practical papers test the third. In other words, more than a third of the marks on the written papers are for applying chemistry to unfamiliar information — data, graphs, new reactions — rather than recalling it. Revising only by rereading notes leaves those marks to chance.

Where marks are lost

The same handful of habits costs IGCSE students marks year after year. Almost none of them are gaps in understanding.

State symbols

The syllabus asks candidates to construct word and symbol equations “including state symbols”. When a question asks for state symbols, an equation without them is incomplete, however well balanced it is. The common slip is (aq) versus (l): water formed in neutralisation is (l), a dissolved salt is (aq). Get into the habit of writing state symbols on every equation you practise, so you do not have to remember to add them under time pressure.

Ionic equations

Extended candidates are expected to write symbol equations with state symbols, including ionic equations. These catch students who know the full equation but are unsure which species to cancel. Spectator ions do not appear; the charges on both sides must balance; and the state symbols still apply. Precipitation and neutralisation are the two you will meet most, so practise those until they are automatic.

Units and significant figures

Calculators may be used throughout, and the syllabus is specific about what it expects in return. A measurement or calculated quantity must be given with a correct unit. Only the final answer in a calculation is rounded, so do not round as you go. And in practical work, a calculated quantity should be given to the same number of significant figures as the least precise raw data used. Watch your volumes, too: the syllabus expects you to convert between cm³ and dm³, and a concentration calculation done in the wrong one is out by a factor of a thousand. Lay out your working so you can still collect method marks if the final value goes wrong.

Tables and readings

The practical papers have their own conventions, and they are set out in the syllabus. Column headings carry the quantity and unit separated by a solidus, such as time / s; units do not go in the body of the table; and readings should reflect the precision of the instrument. These are easy marks if you know the rules, and easy to drop if you write tables the way you would in class notes.

Precise wording

Chemistry has pairs of words that mean different things: atom and ion, strong and concentrated, element and compound. Writing one when the mark scheme needs the other loses the mark even if your idea was right. Pay equal attention to the command word: “state” wants a short answer, “explain” wants a reason, and “describe” wants what happens, not why.

How to practise for it

The quickest way to stop losing these marks is to see them being lost. When you write an answer and have it marked against the mark scheme point by point, you find out that your chemistry was right and a state symbol or a unit cost you the mark — a two-second fix rather than a topic to revise again. That is how every answer is marked on Exaim, against the board’s own mark scheme.

Start with the free Cambridge IGCSE Chemistry revision notes, flashcards, mind maps and worksheets, organised by topic and subtopic, or browse every course from the revision resources page. Then write answers, check which mark points you hit, and redo the ones you missed until the precise version is the one you write first.