Open response questions

Extended open response questions require longer answers than structured questions that have fewer marks. Open response questions are usually worth 6 marks, but some are worth fewer marks.

It is wise to plan your answer first by making some notes. This will help you to include all the key points.

To gain full marks, you need to:

  • support explanations using scientific knowledge and understanding
  • use appropriate scientific words
  • write clearly and link ideas in a logical way
  • maintain a sustained line of reasoning

Open response questions often use these command words:

  • 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.
  • 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.
  • Evaluate means you must use information supplied, or your own knowledge, to consider the evidence for and against or to identify strengths and weaknesses. You must then complete your answer with a conclusion, stating which is better and why, for example.

Open response questions may be synoptic questions, which bring together ideas from two or more topics. For example, a question about fertilisers could include ideas about covalent substances, acids and alkalis, chemical calculations and effects on the environment.

The answers shown here give marking points as bullet points. You do not usually need to include all of them to gain full marks, but you do need to write in sentences, linking them logically and clearly.

This page contains AQA material which is reproduced by permission of AQA.

Sample question 1 - Foundation

Question

The image shows a distance-time graph of a car.

A distance time graph, labelled with points A, B, C and D

Explain what the graph shows about the motion of the car between point A and point E.

You should use values from the graph in your answer. [4 marks]

Indicative content

  • Between A and B car is moving from origin.
  • The gradient of the line shows it's moving at a constant speed.
  • Speed between these points is \frac{250}{20} = 12.5 m/s.
  • Between B and C car is stationary/not moving.
  • Because between these points the graph is flat.
  • Showing that the car's speed is 0 m/s.
  • Between C and D the car is moving further from origin.
  • At constant speed.
  • Speed is \frac{250}{20} = 12.5 m/s.
  • Movement between these points is the same as at A-B.
  • Because the gradient is the same.
  • Between D and E car moves towards origin.
  • At constant speed.
  • Speed is \frac{500}{30} = 16.7 m/s.
  • Gradient between D and E shows that car moves faster or at a greater speed than between any other points.

Sample question 2 - Foundation

Question

A man is driving his car at a constant speed on a wet road.

He sees a fallen tree on the wet road and tries to stop quickly to prevent an accident.

Explain why the man may not be able to stop in time. [6 marks]

Indicative content

  • Overall stopping distance related to thinking distance and braking distance.
  • Factors affecting thinking distance:
    • driver could be distracted
    • driver could be tired
    • driver could be on medication that affects thinking (makes drowsy)
    • driver could have drunk alcohol
    • mean that reaction time will be longer so will not brake as quickly
  • Factors that affect braking distance:
    • condition of car (eg worn brakes means cannot stop as quickly, wear on tyres reduces friction on road)
    • speed car is travelling (faster means more kinetic energy)
    • condition of the road (eg the road is wet so friction between tyres and road reduced)

Sample question 3 - Higher

Question

A salt copper sulfate can be made by reacting copper carbonate with dilute sulfuric acid.

CuCO3(s) + H2SO4(aq) → CuSO4(aq) + H2O(l) + CO2(g)

Write a method that a student could use to prepare a pure, dry sample of copper sulfate.

You do not need to write a risk assessment or include safety points. [6 marks]

Indicative content

  • Pour a suitable volume of sulfuric acid into a suitable container.
  • Add a small amount of copper carbonate to the acid and stir until the effervescence stops.
  • Continue to add small amounts of copper carbonate to the acid and each time stir until any effervescence stops.
  • Eventually when there is no reaction/effervescence when the copper carbonate is added filter the mixture to remove the excess copper carbonate.
  • Pour the filtrate (copper sulfate solution) into an evaporating basin and heat to evaporate a small amount of the water.
  • Leave the copper sulfate solution to crystallise.
  • Remove the crystals from the solution remaining and dry the crystals.