IGCSE Chemistry Paper 4: the 80-mark paper worth half the grade, and how to score on it

Paper 4: Theory (Extended) lasts 1 hour 15 minutes, is worth 80 marks, consists of short-answer and structured questions, and makes up 50% of the grade.

Extended candidates sit three papers: Paper 2, 40 multiple-choice questions (30%) · Paper 4, written (50%) · Paper 5, the practical test, or Paper 6, the alternative to practical (20%), and can be awarded A* to G. Core candidates sit Paper 1 and Paper 3 instead, with grade C as the highest.

All of this is from the Cambridge IGCSE Chemistry 0620 syllabus for exams in 2026, 2027 and 2028.

75 minutes for 80 marks is under a minute per mark. A question ending in [2] deserves about two minutes, and the number in brackets also tells you how many points the examiner is looking for.

Stuck for too long? Move on and come back. An easy mark at the end of the paper is worth exactly as much as a hard one at the start.

The syllabus weights Papers 3 and 4 at about 63% knowledge with understanding (AO1) and 37% handling information and problem-solving (AO2). Roughly a third of the marks come from reading a table, a graph or given data and then concluding, calculating or explaining.

Cambridge also says these questions may be set in situations students have not met, applying the principles they know to something new. Memorising alone will not reach an A*.

The first word of the question says what the examiner wants. State wants a short answer, Describe wants what you see or the main features, Explain wants the reasons why or how. Students who know the content often lose marks by answering the wrong kind of question, for example describing what happens when asked to explain.

Tap through the common ones below. The English meanings are quoted from the syllabus.

A mark scheme awards marks point by point (marking points), not for length or style. A short answer with every key point gets full marks; a long one that misses a point does not.

Pick an answer below and see what it scores. Notice that the answers scoring 1 out of 2 usually have the right idea but only half the reasoning.

Writing only the final answer to a calculation. If it is wrong, there is no working for the examiner to give partial credit for. Show every step and always give units.

Unbalanced equations, or missing state symbols when the question asks for them.

Naming a substance when asked to describe an observation, such as "hydrogen is produced" instead of "bubbles" (you cannot see that it is hydrogen; you can see the bubbles).

Swapping words that mean different things: strong and concentrated, or more collisions and more frequent collisions.

Do past papers timed at 1 hour 15 minutes, mark them yourself against the mark scheme, and keep every missing key word in one notebook to reread before the exam.

Mole calculations are Supplement content, so they appear on Papers 2 and 4. Make them automatic.

On Boom-Tutor, a bank of Paper 4-style questions will let AI mark the answers you write against the mark scheme and point out the missing points, with auto-marked mocks. The course is ฿4,900, paid once. The platform is expected to open around December 2026.