# 4-mark practice questions — OCR GCSE Chemistry A: Gateway Science (J248)

> 83 questions · chemistry

## How to answer

4-mark questions are the shortest levels-of-response band. Aim for four scientific ideas, each in its own short sentence.

## Sample questions

1. [A food scientist is investigating whether a sample of red food colouring is pure or a mixture of dyes. She uses paper ch…](https://www.gradenine.co.uk/q/a-food-scientist-is-investigating-whether-0a28ccd7)
2. [A scientist carries out electrolysis of molten lead bromide using inert electrodes. Explain what happens at each electro…](https://www.gradenine.co.uk/q/a-scientist-carries-out-electrolysis-of-12d38ed2)
3. [Explain why phytomining is considered a more sustainable method of metal extraction than traditional mining, and describ…](https://www.gradenine.co.uk/q/explain-why-phytomining-is-considered-a-255707a0)
4. [Describe how steam cracking is used to produce smaller, more useful molecules from crude oil fractions, and explain why …](https://www.gradenine.co.uk/q/describe-how-steam-cracking-is-used-25703852)
5. [Describe how scientists' understanding of atomic structure changed from Dalton's model to Rutherford's nuclear model, in…](https://www.gradenine.co.uk/q/describe-how-scientists-understanding-of-atomic-27a9deae)
6. [Explain why graphite can conduct electricity but most other giant covalent structures, such as diamond, cannot.](https://www.gradenine.co.uk/q/explain-why-graphite-can-conduct-electricity-282d900a)
7. [A student is trying to identify the gases produced during an experiment. Describe the tests a student would carry out to…](https://www.gradenine.co.uk/q/a-student-is-trying-to-identify-33760b2f)
8. [Describe how carbon dioxide emissions from human activity contribute to climate change, and explain one consequence of t…](https://www.gradenine.co.uk/q/describe-how-carbon-dioxide-emissions-from-3917fa43)

## Related

- [OCR GCSE Chemistry A: Gateway Science (J248) revision notes](https://www.gradenine.co.uk/learn/ocr-gcse-chemistry-a-gateway-science-j248)
- [OCR GCSE Chemistry A: Gateway Science (J248) past papers](https://www.gradenine.co.uk/past-papers/ocr-gcse-chemistry-a-gateway-science-j248)
- [Practise with AI marking (free)](https://www.gradenine.co.uk/start)