Different Half-lives Of Radioactive Isotopes (GCSE Physics)

In radiocarbon dating, a sample contains 25% of the modern C-14 activity. Approximately how old is it (using C-14 half-life 5700 years)?

A rock sample has a radioactive isotope whose half-life is 64.37 s. After 257.48 s (4 × 64.37 s) the activity will be what fraction of original?

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

A medical isotope should have a short half-life to minimize patient dose but long enough to perform the procedure. Which half-life property best matches this need?

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

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

Which formula gives the fraction of nuclei remaining after time t for an isotope with half-life T?

A half-life is the time taken for half of a sample of unstable nuclei to decay.

An isotope used in diagnostics has half-life of minutes; which handling practice is most important?

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?

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?