Command words in SPM Chemistry: state, explain, describe

Every written SPM Chemistry question begins with a command word, and that word is an instruction about the shape of answer the examiner wants. Two students can know exactly the same chemistry and score differently because one answered the command word and the other did not. If you learn what each command word demands, you stop giving a one-line fact where a full explanation was needed, or writing a paragraph where a single word would have scored. This post works through the most common ones with model answers.

State and give: a fact, no reason

“State” and “give” ask for a fact, a name or a value, nothing more. No reasoning is expected, and adding it wastes time you need elsewhere. Keep the answer short and exact.

• Question: State the colour of the precipitate formed when sodium hydroxide solution is added to copper(II) sulfate solution.
• Model answer: Blue.

That is a complete answer for a “state” mark. A whole sentence of explanation would earn no extra credit here.

Define: the exact meaning, in the right terms

“Define” asks for the precise meaning of a term, using the wording the syllabus expects. Definitions are recall marks, so learn them exactly rather than paraphrasing loosely.

• Question: Define the term isotopes.
• Model answer: Isotopes are atoms of the same element with the same number of protons but a different number of neutrons.

Notice both halves are needed: same protons and different neutrons. Drop either and the definition is incomplete. You can check the exact wording of key terms on our glossary.

Explain: a fact plus its reason

“Explain” is where most marks are won and lost. It asks not just what but why, a statement followed by the reason behind it, usually linked with “because” or “since”. A bare fact answers only half an “explain” question.

• Question: Explain why magnesium has a higher melting point than sodium.
• Model answer: Magnesium has a higher melting point because each magnesium atom releases two valence electrons to the sea of delocalised electrons, while sodium releases one. The stronger metallic bond, from a greater number of delocalised electrons and a higher ionic charge, needs more heat energy to overcome.

The statement is the melting point comparison; the reason is the bonding. Both together earn the marks.

Describe: the full sequence of what happens

“Describe” asks you to set out what happens, what you would observe, or the steps of a procedure, in order and in enough detail that someone could follow it. This is common in qualitative analysis and in practical questions.

• Question: Describe a chemical test to confirm that a gas is carbon dioxide.
• Model answer: Bubble the gas through limewater. If the gas is carbon dioxide, the limewater turns from colourless to milky (a white precipitate forms).

A good “describe” answer names the reagent, the action, and the observed result. It appears throughout the practical work you can revise on our experiments hub.

Compare: both sides, with a linking word

“Compare” wants both things set against each other, not two separate descriptions sitting side by side. Use a linking word, “whereas”, “while”, “but”, so the contrast is explicit and the examiner can see you are comparing, not just listing.

• Question: Compare the electrical conductivity of sodium chloride when solid and when molten.
• Model answer: Solid sodium chloride does not conduct electricity because its ions are held in fixed positions in the lattice, whereas molten sodium chloride conducts because the ions are free to move and carry charge.

The word “whereas” is doing real work: it turns two facts into a comparison.

Suggest and predict: apply what you know to a new case

“Suggest” and “predict” tell you the answer is not a memorised fact, you must apply a principle to an unfamiliar situation. There may be more than one acceptable answer, so a sensible, chemically justified response scores.

• Question: Suggest why a car body made of iron is more likely to rust near the sea.
• Model answer: Sea air contains salt (sodium chloride) dissolved in moisture. The salt solution is an electrolyte that speeds up the rusting of iron, so the car body corrodes faster.

You are rewarded for applying the idea that an electrolyte accelerates rusting, not for having memorised this exact scenario.

Calculate and determine: show every step

“Calculate” and “determine” require a numerical answer with working. Method marks are awarded for the steps even if the final number slips, so always write the formula, substitute the values, then compute, and finish with the correct unit. We cover how these steps map onto the mark scheme in our guide to how the marking scheme works.

Match your answer to the word

Before you write, underline the command word and let it set the length and shape of your answer: a single term for “state”, a two-part reason for “explain”, an ordered sequence for “describe”, a linked contrast for “compare”. This is especially decisive in the longer answers of Paper 2 Section C, where a question mixing “explain” and “describe” rewards you for handling each part in its own way.

Command words are free marks once you train the habit of reading them first. If you would like a teacher to mark your answers against the command word, the way an examiner does, our online one-to-one lessons run in English from RM50 an hour, with a paid one-hour trial, our experienced SPM Chemistry teachers and our team make this one of the first habits we build with a new student.