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IGCSE · Practice questions · Extraction and the reactivity series

Carbon or current?

Six original Cambridge-style questions on the extraction of metals and the reactivity series.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Above carbon: electrolysis. Below: carbon.

01
Recall
[1 marks]

Define the term ore.

  • A rock that contains enough of a metal (compound) to make extraction economically worthwhile. ✓
02
Explain
[2 marks]

Explain why zinc can be extracted by heating zinc oxide with carbon, but aluminium cannot be extracted from aluminium oxide this way.

  • Zinc is below carbon in the reactivity series, so carbon can remove oxygen from zinc oxide. ✓
  • Aluminium is above carbon, so carbon cannot reduce aluminium oxide; electrolysis is needed. ✓
03
Recall
[2 marks]

Write a balanced equation for the reduction of zinc oxide by carbon, and identify the reducing agent.

  • 2ZnO + C → 2Zn + CO2 (or ZnO + C → Zn + CO). ✓
  • Carbon is the reducing agent. ✓
04
Analysis
[3 marks]

Suggest a method of extraction for each metal: (a) potassium, (b) lead (below iron in the series), (c) gold.

  • (a) electrolysis of a molten potassium compound. ✓
  • (b) reduction of lead oxide by carbon. ✓
  • (c) found uncombined; no chemical extraction needed. ✓
05
Explain
[2 marks]

Suggest two reasons why carbon is used to extract metals such as iron.

  • Carbon (coke) is cheap and readily available. ✓
  • It is more reactive than iron, and burning it also provides the high temperature needed. ✓
06
Explain
[2 marks]

Suggest why aluminium, though very common in the Earth's crust, was expensive before large-scale electricity was available.

  • Aluminium is too reactive to be extracted with carbon. ✓
  • It can only be extracted by electrolysis, which needs large amounts of electricity. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.