IB Physics · E.3 · structured
Decay after 2 half-lives
Nuclear and quantum physics · Radioactive decay · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- routine
- Marks
- 5
- Topics
- 2
- Answer
- Complete
Question5 marks
A sample initially contains 4.80 × 106 unstable nuclei and has half-life 4 h. How many unstable nuclei remain after 8 h, and what fraction is this?
Task interpretation
What a complete response should do
Build a visible chain from the information given to the quantity or statement requested.
Name the standard relationship first, keep units attached, and show the substitution before the result.
- Response type
- structured
- Allocation
- 5 marks
- Demand
- routine
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Use your answer and the marking steps—not confidence alone—to choose.