Different Half-lives Of Radioactive Isotopes (GCSE Physics)

Which statement is true: a shorter half-life implies which of the following?

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 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?

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

If a sample undergoes 3 half-lives, what fraction of the original nuclei remains?

Which of these isotopes (half-lives in seconds) is the longest lived: N-18 = 0.62 s, N-17 = 4.17 s, F-17 = 64.37 s, F-18 = 6584.34 s?

An isotope has half-life T. Which expression gives the number of half-lives elapsed in time t?

If activity (count rate) of a source is 1600 Bq, what will its activity be after 2 half-lives?

If an isotope’s activity halves every 5 years, how long until activity is 6.25% of original?

You measure a sample’s remaining fraction to be (1/2)^(t/T) and rearrange to find T. To estimate half-life from measured N0 and N after time t, which equation is correct?

A sample’s activity falls to one-quarter of its original value. How many half-lives have passed?