Half-Life Calculations-More Practice

Front

What is half-life?

Back

Half-life is the time required for half of the radioactive atoms in a sample to decay.

Front

How do you calculate the remaining amount of a substance after a certain number of half-lives?

Back

Remaining amount = Initial amount × (1/2)^(number of half-lives)

Front

If the half-life of a substance is 25 years, how much will remain after 100 years if you start with 4.0 g?

Back

0.25 g

Front

What percentage of a radioactive isotope remains after 2 half-lives?

Back

25% of the original amount remains after 2 half-lives.

Front

What is the half-life of an isotope if it takes 10 seconds for half of it to decay?

Back

10 seconds.

Front

If you need 6.25 g of Zn-71 for an experiment and its half-life is 2.4 minutes, how much should you prepare if it will take 9.6 minutes before the experiment?

Back

100.0 g

Front

After 22,800 years, what percentage of the original carbon-14 remains?

Back

6.25%.

Front

What is the formula to find the initial amount needed based on half-life?

Back

Initial amount = Final amount / (1/2)^(time elapsed / half-life)

Front

If a substance has a half-life of 5 years, how much will remain after 15 years if you start with 80 g?

Back

10 g.

Front

What is the significance of half-life in radioactive dating?

Back

Half-life helps determine the age of artifacts by measuring the remaining radioactive isotopes.