Using Resources: Exam Practice

This lesson brings together all the key topics from the AQA GCSE Chemistry Using Resources unit. It is designed to help you consolidate your knowledge, identify common exam question types, and practise applying your understanding to the kinds of questions that appear on the AQA papers.

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Key Topics Checklist

Before you begin exam practice, make sure you are confident with all of the following topics. Use this table to identify any areas you need to revise further:

Topic	Key Points You Must Know
Using Earth's resources	Finite vs renewable; natural vs synthetic; sustainable development
Potable water	Definition; difference from pure water; treatment process (sedimentation, filtration, sterilisation)
Desalination	Distillation and reverse osmosis; why it requires lots of energy
Required practical: water purification	Distillation apparatus and method; testing for chloride ions; testing for dissolved solids
Waste water treatment	Sources; stages (screening, primary, secondary, sludge treatment); aerobic vs anaerobic
Extracting metals from low-grade ores	Phytomining; bioleaching; displacement and electrolysis to obtain copper
Life cycle assessments	Four stages; limitations (subjectivity, bias); comparing products
Reduce, reuse, recycle	Waste hierarchy; recycling metals, glass and plastics; advantages and limitations
Corrosion and alloys	Rusting conditions; prevention methods; sacrificial protection; alloy structure and properties
Ceramics, polymers and composites	Properties of each; thermosoftening vs thermosetting; composite structure (matrix + reinforcement)

Exam Tip: Use this checklist as a self-assessment tool. If you cannot confidently explain all the key points for a topic, go back and revise that lesson before attempting exam-style questions.

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Common Command Words

Understanding what the examiner is asking is crucial. Here are the command words you will encounter:

Command Word	What You Must Do
State	Give a brief, factual answer with no explanation needed
Describe	Give an account of what something is or how it works
Explain	Give reasons why something happens; use scientific knowledge
Compare	Identify similarities and differences between two or more things
Evaluate	Consider evidence from both sides and reach a supported conclusion
Suggest	Apply your knowledge to an unfamiliar context; there may be more than one valid answer
Calculate	Work out a numerical answer; show your working
Justify	Give reasons for a decision or conclusion

Exam Tip: "Explain" and "Describe" are NOT the same. Describe = say what happens. Explain = say what happens AND why. If a question says "explain", you must give a reason or mechanism, not just a description.

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Exam Practice: Short Answer Questions

Question Type 1: Definitions and Key Terms

These questions test recall of key vocabulary. Practise writing concise definitions.

Term	Model Definition
Potable water	Water that has sufficiently low levels of dissolved salts and microorganisms to be safe to drink
Sustainable development	Development that meets the needs of the current generation without compromising the ability of future generations to meet their own needs
Corrosion	The destruction of a metal by chemical reaction with substances in its environment
Alloy	A mixture of two or more elements, at least one of which is a metal
Composite	A material made from two or more different materials, where the components can still be distinguished
Life cycle assessment	An analysis of the environmental impact of a product at every stage of its life, from raw material extraction to disposal
Finite resource	A resource that is being used faster than it can be replenished and will eventually run out
Phytomining	Using plants to absorb metal ions from soil; the plants are harvested and burned to extract the metal from the ash
Bioleaching	Using bacteria to extract metals from low-grade ores by producing acidic solutions that dissolve metal compounds

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Exam Practice: Process Questions

Question Type 2: Describing Processes

graph TD
    A[Process Questions] --> B[Water Treatment]
    A --> C[Sewage Treatment]
    A --> D[Metal Extraction]
    A --> E[Recycling]
    B --> B1["Fresh water:<br>Sedimentation -> Filtration -> Sterilisation"]
    B --> B2["Seawater:<br>Distillation or Reverse Osmosis"]
    C --> C1[Screening -> Sedimentation -> Aerobic treatment]
    C --> C2[Sludge: Anaerobic digestion -> Biogas + Fertiliser]
    D --> D1[Phytomining: Grow plants -> Harvest -> Burn -> Extract from ash]
    D --> D2[Bioleaching: Bacteria -> Leachate -> Displacement or Electrolysis]
    style A fill:#e3f2fd,stroke:#1565c0
    style B fill:#bbdefb,stroke:#1565c0
    style C fill:#c8e6c9,stroke:#2e7d32
    style D fill:#fff9c4,stroke:#f57f17
    style E fill:#e1bee7,stroke:#6a1b9a

When describing a process, follow these rules:

1. Use the correct sequence — examiners check that steps are in the right order
2. Name specific substances — e.g. "chlorine" not just "a chemical"
3. State the purpose of each step — e.g. "filtration removes fine insoluble particles"
4. Use scientific vocabulary — e.g. "sedimentation" not just "the stuff settles"

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Exam Practice: Comparison Questions

Question Type 3: Comparing Methods or Materials

AQA frequently asks you to compare two things. Always use a structured approach:

Example: Compare producing potable water in the UK with desalination.

Feature	UK Water Treatment	Desalination
Source	Fresh water (rivers, lakes, reservoirs)	Seawater or brackish water
Process	Sedimentation, filtration, sterilisation	Distillation or reverse osmosis
Energy requirement	Relatively low	Very high
Cost	Relatively low	Very expensive
When used	Where there is adequate rainfall	Where fresh water is scarce

Example: Compare barrier methods and sacrificial protection for preventing rusting.

Feature	Barrier Methods	Sacrificial Protection
How it works	Physical barrier prevents water and oxygen reaching the iron	A more reactive metal corrodes instead of the iron
Examples	Painting, oiling, plastic coating, electroplating	Galvanisation (zinc coating), zinc/magnesium blocks
If coating is damaged	Iron is exposed and rusting begins immediately	Iron is still protected as long as the reactive metal is in contact
Maintenance	Coating must be reapplied if damaged	Sacrificial blocks must be replaced periodically

Exam Tip: In comparison questions, make sure your points are directly comparative. Do not describe one method and then describe the other separately — for each feature, state what happens in both cases. Use linking words like "whereas", "however" and "in contrast".

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Exam Practice: Evaluation Questions

Question Type 4: Evaluating Materials or Methods (6-mark Questions)

Six-mark extended response questions require you to:

1. Make relevant points with scientific detail
2. Consider both sides (advantages and disadvantages)
3. Reach a supported conclusion
4. Use correct scientific terminology
5. Organise your answer logically

Planning a 6-Mark Answer

Use this framework:

Section	What to Include
Introduction	Briefly state what you are evaluating
Advantages / For	2-3 detailed points with scientific reasoning
Disadvantages / Against	2-3 detailed points with scientific reasoning
Conclusion	A balanced judgement supported by the evidence you have presented

Example question: Evaluate the use of phytomining and bioleaching as methods of extracting copper.

Model answer structure:

• For: Can extract copper from low-grade ores and mine waste that would otherwise be uneconomic; lower energy requirements than smelting; less environmental damage than traditional mining (no large-scale excavation)
• Against: Very slow (months to years); produces acidic/toxic waste solutions (bioleaching); requires large areas of land (phytomining); copper yield is relatively low
• Conclusion: These methods are useful supplements to traditional mining, especially for extracting metals from waste or low-grade ores, but their slow speed means they cannot fully replace conventional extraction

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Common Mistakes to Avoid