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Home · IGCSE 0625 · Nuclear physics · Nuclear fission and fusion · Practice
Extended · Practice questions · Nuclear fission and fusion
Supplement (Extended) content

Split it, or join it.

Six original Cambridge-style questions on fission and fusion: describing each process, the chain reaction, why fusion needs heat, and telling the two apart.

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.
What the examiner wants

Right process, right direction.

01
Recall
[3 marks]

Describe what happens to a heavy nucleus in nuclear fission.

  • It absorbs a neutron and becomes unstable. ✓
  • It splits into two lighter nuclei, releasing energy. ✓
  • Two or three more neutrons are also released. ✓
02
Analysis
[3 marks]

Explain how a chain reaction is set up in a sample of fissionable material.

  • Each fission releases two or three neutrons. ✓
  • These neutrons are absorbed by other nuclei, making them split too. ✓
  • If enough nuclei are present, the reaction keeps itself going. ✓
03
Recall
[2 marks]

Describe what happens in nuclear fusion.

  • Two light nuclei join together to form a heavier nucleus. ✓
  • Energy is released. ✓
04
Analysis
[2 marks]

Explain why fusion can only happen at very high temperatures.

  • The two nuclei are positively charged and repel each other. ✓
  • Only at very high temperatures do they move fast enough to get close enough to join. ✓
05
Application
[2 marks]

State which process, fission or fusion, is used in a nuclear power station, and which provides the energy of the Sun.

  • A nuclear power station uses fission. ✓
  • The Sun is powered by fusion. ✓
06
Application
[2 marks]

State the main difference between fission and fusion, and one thing that is the same about them.

  • Difference: fission splits a heavy nucleus into lighter ones, while fusion joins light nuclei into a heavier one. ✓
  • Same: both release energy from the nucleus. ✓

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.