How to Answer State, Describe, Explain, Suggest and Compare Questions in Cambridge IGCSE Chemistry (0620)

Knowing the Chemistry is only part of answering an exam question correctly. You can understand the topic, recognise the reaction and remember the relevant equation, but still lose marks because your response does not do what the command word asks. In Cambridge IGCSE Chemistry (0620), words such as State, Describe, Explain, Suggest and Compare change the task in front of you. A strong answer starts by identifying both the Chemistry being tested and what the command word requires you to do with it.

What the five command words are asking you to do

The current Cambridge IGCSE Chemistry (0620) syllabus for 2026–2028 includes a command-word table and notes that the meaning of each word has to be read in the subject context. That matters because the same word can appear in questions about particles, bonding, practical work, electrolysis, organic Chemistry or metals. The definition tells you the type of response required; the Chemistry in the question tells you what that response must contain.

State: give the requested information clearly

Cambridge uses State when the answer should express the required information in clear terms. In Chemistry, that may be a property, condition, observation, formula, type of bonding or purpose of a piece of apparatus. The safest response is usually the direct answer first. Do not automatically turn a State question into an Explain question. The syllabus itself makes the distinction visible. In the States of Matter topic, candidates are expected to state the distinguishing properties of solids, liquids and gases, while other learning objectives ask them to describe particle structures and explain changes of state using kinetic particle theory. The content is related, but the action changes. This does not mean every State question is one mark or one sentence. A question can ask you to state more than one piece of information. The useful rule is simpler: give what was requested without burying it inside unnecessary reasoning.

Describe: make the relevant features or observations clear

A Describe response needs the points, characteristics or main features of what the question names. In Chemistry, that often means describing an observation, a trend, the structure of particles, an experimental method or what happens during a reaction. If the question asks for an observation, write what could actually be seen: a colour change, a precipitate, effervescence, a solid disappearing or another relevant visible change. One common mistake is answering a Describe question with the reason instead of the description. If a question asks you to describe a trend down Group VII, the first job is to state how the relevant property changes. If it asks you to describe an experimental test, the method and observation need to be clear. The chemical explanation only belongs there if the question also asks for it. A useful check is to read the noun after the command word. "Describe the observation", "describe the structure" and "describe the trend" all use the same command word, but they ask for different kinds of information.

Explain: make the reason or relationship visible

An Explain answer has to go beyond a correct fact. Cambridge uses Explain when you need to set out a reason, show why or how something happens, or make the relationship between ideas clear. This is where otherwise knowledgeable answers often stop one step too early. For example, saying that particles have more kinetic energy at a higher temperature is relevant to a rates question, but if the question asks why the reaction becomes faster, the reasoning has to continue into collisions and successful collisions. Likewise, identifying delocalised electrons in a metal is useful knowledge, but an explanation of electrical conductivity needs to connect their movement to the transfer of charge. The exact depth depends on the question and the marks available. There is no universal Cambridge formula such as "two sentences for two marks". Instead, ask: have I shown the scientific link that turns the fact into the outcome? If the examiner still has to infer that link, the explanation is probably incomplete.

Suggest: apply Chemistry to the situation in front of you

Suggest is different from straightforward recall. The current syllabus defines it around applying knowledge and understanding where more than one valid response may be possible. That is why Suggest questions can feel unfamiliar even when the Chemistry needed to solve them is familiar.

In the magnesium-and-steam practical shown below, part (b) asks how the magnesium ribbon should be cleaned before use, while part (c) asks candidates to state the purpose of the mineral wool. The first task needs a scientifically sensible proposal in context; the second asks for the required function directly. A valid suggestion is to clean the ribbon with abrasive paper so the surface oxide layer is removed before heating.

Click to enlarge

The key is that Suggest does not mean guess. Use the information provided, connect it to a Chemistry principle and propose something that works scientifically. If a practical setup, graph or unfamiliar substance is given, treat those details as clues rather than background decoration.

Compare: put the relationship between both sides on the page

Cambridge defines Compare as identifying or commenting on similarities and/or differences. The "and/or" matters. You should follow the exact wording of the question rather than assuming every comparison must contain a fixed number of similarities and differences. The clearest Chemistry comparisons are usually paired. Instead of writing everything you know about substance A and then everything about substance B, compare one property at a time. For example: "solid magnesium conducts electricity, whereas solid magnesium chloride does not." The relationship is visible immediately. If the question then asks you to explain the difference, you can move into metallic bonding, delocalised electrons and the fixed ions in a solid ionic lattice. The current (0620) syllabus explicitly expects students to compare general physical properties of metals and non-metals, including thermal conductivity, electrical conductivity, malleability, ductility, melting points and boiling points. That is a good reminder that comparison is not a writing trick. It is a way of organising accurate Chemistry so that the relationship being tested is unmistakable.

Do not turn command words into rigid answer formulas

Command words tell you the kind of response required, but they do not create a universal sentence-counting system. A two-mark State question might contain two separate pieces of information. A Suggest question might need a proposal plus a condition that makes it valid. An Explain question might require several connected ideas because the relationship itself has several stages. This is why rules such as "one sentence per mark" are unreliable. Use the marks to judge the scale of the task, but use the actual question and marking guidance to decide what earns credit. The better check is command-word specific: did you state exactly what was requested, describe the relevant feature, explain the reason, suggest something that fits the context, or compare the two sides directly?

Review command-word mistakes after you attempt the question

If command words regularly cost you marks, memorising their definitions is not enough. You need to find out what your own answers are doing wrong. You may know the Chemistry but stop an Explain response one link too early. You may give the chemical reason when a Describe question wanted an observation. You may make a plausible Suggest answer that does not fit the apparatus or information provided. Inside NeuraGeek, you can attempt the real question first and then use the paper, mark scheme and Paper Tutor together to diagnose the gap. In the magnesium example, Paper Tutor separates the suggestion from the State response and can explain why the answer works after the attempt. That explanation is useful for learning even when the exam answer itself can be much shorter.

Click to enlarge

A simple command-word check before you move on

Before leaving a written Chemistry question, look at the command word one more time. For State, have you given the requested information clearly? For Describe, have you made the relevant features, observations or stages visible? For Explain, have you shown why or how? For Suggest, have you applied Chemistry to the specific situation? For Compare, have you actually put the two sides in relation to each other? The goal is not longer answers. It is to make the answer perform the task Cambridge has actually set. Once these distinctions become automatic, you can spend less time guessing at structure and more time showing the Chemistry you know.