How to Answer A-Level Chemistry Exam Questions (and Stop Losing Easy Marks)

A-Level Chemistry8 min read

Most A-Level Chemistry marks are lost on exam technique, not chemistry knowledge: missing state symbols, ignoring the command word, rounding too early in calculations, and not showing working. Fix those habits and a grade B becomes an A. This guide walks through each one with worked examples for AQA, Edexcel and OCR.

1. Read the command word first

The command word tells you exactly what the examiner wants. Answering the wrong verb is the single most common way students lose marks they clearly know the chemistry for.

  • State / Give / Name, one short fact, no explanation needed.
  • Describe, say what happens, in order, but not why.
  • Explain, say why it happens, using chemical reasoning (this is where the marks are).
  • Suggest, apply what you know to an unfamiliar context; there may be more than one valid answer.
  • Calculate, show working and give a numerical answer with the correct unit.
  • Deduce, reach a conclusion and justify it from the data given.
Common mistake
  • Writing a description when the question says 'explain'. 'The rate increases' is a description; 'the rate increases because more particles have energy above the activation energy' is an explanation, and only the second scores the explain mark.

2. Balance the equation and include state symbols

In equation questions there is usually a mark for the correct balancing and a separate mark for state symbols. Students who know the reaction still routinely drop the second mark by leaving state symbols off.

For example, the neutralisation of sodium hydroxide with hydrochloric acid:

  • NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)
Tutor tip
  • Add state symbols to every equation you write, even in working. It becomes automatic, so you never lose the mark under pressure.

3. Show every step and don't round too early

Calculation questions award method marks for working, so a wrong final answer can still score most of the marks if the steps are shown. The classic error is rounding intermediate values, which drifts the final answer outside the mark-scheme tolerance.

  1. 1Write the relationship: moles = mass / Mr
  2. 2Substitute: For 4.00 g of NaOH (Mr = 40.0): moles = 4.00 / 40.0
  3. 3Answer with the right precision: = 0.100 mol, quoted to 3 significant figures to match the data
Common mistake
  • Rounding to 2 significant figures halfway through, then carrying that rounded number forward. Keep full precision on your calculator until the final line, then round once.

4. 'Explain' answers need an effect and a reason

Le Chatelier questions are worth easy marks if you always pair the change with its consequence. Name the shift, then justify it.

For the Haber process, N2(g) + 3H2(g) ⇌ 2NH3(g): increasing the pressure shifts the equilibrium to the right, because the right-hand side has fewer moles of gas (2 versus 4), so the yield of ammonia increases.

Tutor tip
  • Structure every equilibrium answer as: which way it shifts, plus why (moles of gas, or exo/endothermic direction). Two clauses, two marks.

5. Use the right level of detail in organic answers

Mechanism marks are precise. Curly arrows must start from a bond or a lone pair and point to exactly where the new bond forms. Skeletal shortcuts that hide the relevant bond usually lose the arrow mark.

  • Draw the arrow from the electron source (a lone pair or a bond), not from the atom label.
  • Show the arrow ending where the new bond forms, or onto the atom that gains the lone pair.
  • Keep displayed formulae where the mark scheme needs the bond shown; don't switch to skeletal mid-mechanism.
Common mistake
  • Starting a curly arrow from the positive charge or from an atom symbol instead of from a bond or lone pair. Examiners mark the origin of the arrow strictly.

6. In analysis questions, quote the data

When a question gives a graph or table, your answer has to refer back to it. General statements score less than answers that quote specific values, trends and anomalies.

  • Quote actual numbers and units from the data, not just 'it goes up'.
  • Identify anomalies explicitly and, if asked, suggest a cause.
  • Mention uncertainty or repeats when the question is about reliability.

Frequently asked questions

How many A-Level Chemistry marks are lost on exam technique rather than knowledge?
It varies by student, but exam-technique errors (missing state symbols, misreading command words, rounding too early, not showing working) commonly account for several marks per paper, which is often the difference between one grade and the next. These are the fastest marks to recover because they don't require learning new content.
What are command words in A-Level Chemistry?
Command words are the instruction verbs in a question, such as state, describe, explain, suggest, calculate and deduce. Each demands a specific type of answer: 'describe' asks what happens, while 'explain' asks why. Answering the wrong command word is a frequent cause of lost marks.
Do you still get marks if your final calculation answer is wrong?
Usually yes. Calculation questions award method marks for correct working, and error-carried-forward means a mistake early on doesn't automatically lose the later marks, as long as your steps are shown. This is why you should always write out every step rather than just the final number.
How should I revise A-Level Chemistry exam technique?
Work through past papers with the mark scheme beside you and check how marks are awarded, not just whether your answer was right. A tutor can accelerate this by spotting the specific habits costing you marks. StudyGuru's A-Level Chemistry tutors do exactly this in one-to-one sessions, and you can try it with a £15 Starter Pack.

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