Physics · May / June 2026 · Paper 11 · Question 37

Most household smoke detectors contain a sample of an isotope of americium. The battery in a smoke detector is replaced very frequently, but the sample of the isotope of americium does **not** need to be replaced. Why does the americium isotope **not** need to be replaced?

1. AThe isotope generates its own voltage.
2. BThe isotope has a long half-life.
3. CThe isotope is stable.
4. DThe isotope is dangerous to handle.

As printed in the paper