Different Half-lives Of Radioactive Isotopes (GCSE Physics)

An isotope has half-life 5 years. After 15 years what fraction remains?

A sample’s activity is 10 000 Bq initially. After time t it is 625 Bq. How many half-lives occurred?

A sample’s activity is 3200 Bq initially. After 6 hours it is 400 Bq. What is the number of half-lives that have passed?

Which statement best describes a hazard from internal contamination with an alpha emitter compared to external alpha irradiation?

Two isotopes have the same activity today. Isotope X has half-life 100 years, isotope Y has half-life 1000 years. Which has the larger number of radioactive nuclei now?

You measure that activity dropped from 10 000 Bq to 1250 Bq. How many half-lives elapsed?

What is the SI unit for radioactivity (activity)?

If two isotopes have the same mass of sample but isotope A has a much shorter half-life than isotope B, which is true initially?

Isotope A has half-life 2 days, Isotope B half-life 10 days. Which is more suitable to use as a medical diagnostic tracer that must decay quickly?

Carbon-14 has half-life about 5700 years. After 11 400 years what percentage of the original C-14 remains?

A sample initially contains 800 radioactive atoms. After 4 half-lives how many atoms remain?