Structured questions and short answer questions
Questions with 1, 2, 3 or 4 marks usually start with command words. If a question starts with the command word 'state', 'give', 'name' or 'write down', it needs a short answer only. This type of question can often be answered with one word or phrase.
It is important to state, give, name or write down the number of things that the question asks for. If you write down fewer, you cannot get all the marks. If you write down more, and one is wrong, you might lose a mark.
Learn about command words with Dr Alex Lathbridge
Listen to the full series on BBC Sounds.
Understanding the different command words in your science GCSE exams.
Some questions start with the command words 'describe', 'explain' or 'compare'. These are often worth two or more marks:
- Describe means you should recall facts, events or processes accurately. You might need to give an account of what something looked like, or what happened.
- Explain means you need to make something clear, or state the reasons for something happening. The points in the answer must be linked together. The answer must not be a list of reasons. All the points must be relevant to the question.
- Compare means you need to describe similarities and differences between things. If you are asked to compare X and Y, write down something about X and something about Y and give a comparison. Do not just write about X only or Y only.
More complex structured questions will be worth three or four marks. They include questions with complex descriptions, explanations and questions in which you need to compare things.
Some of the answers are shown here as bullet points. This is to show clearly how a mark can be obtained. However, do not use bullet points in your answers - the points must be linked together logically.
This page contains AQA material which is reproduced by permission of AQA.
Sample question 1 - Foundation
Question
When dilute hydrochloric acid is reacted with sodium hydroxide solution there is a temperature change.
Explain how the temperature changes. [2 marks]
It goes up/increases [1] because the reaction is exothermic/transfers energy to the surroundings [1].
Sample question 2 - Foundation
Question
Catalysts are used in chemical reactions in industry.
Give two properties of catalysts.
For each property, explain why it makes the catalyst useful in industry. [2 marks]
Catalysts increase rate of reaction [1], so the products form in less time [1].
or
Catalysts lower activation energy [1], so lowers energy requirements [1].
or
Catalysts not used up in the reaction [1], so only an initial outlay needed [1].
or
Only a small amount of catalysts needed [1], so small initial cost [1].
One mark is allowed for each property and one mark for each explanation.
The explanation must be linked correctly to the property to gain the mark.
Sample question 3 - Higher
Question
Farmers use ammonium nitrate as a fertiliser.
Farmers want to slow down the rate at which ammonium nitrate fertiliser dissolves in the water in the soil.
Suggest why they spread the fertiliser in the form of small beads instead of a fine powder. [2 marks]
Small beads would dissolve slower than fine powder [1] because the surface area of the bead is less than fine powder [1].
Sample question 4 - Higher
Question
The reaction used to make ammonia is:
N2(g) + 3H2(g) ⇌ 2NH3(g)
The forward reaction is exothermic.
At equilibrium, about 35% of the nitrogen and hydrogen are converted to ammonia at 450°C and 200 atmospheres pressure.
Explain the effects of increasing the temperature, or decreasing the pressure, on the amount of ammonia produced at equilibrium. [4 marks]
Increasing the temperature at equilibrium will reduce the amount of ammonia produced [1] because the reaction is exothermic [1].
Increasing the pressure at equilibrium will increase the amount of ammonia produced [1] because the equilibrium will shift towards the smaller number of molecules in the equation (which is ammonia) [1].
