Half-Life

Front

What is half-life?

Back

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

Front

What is the half-life of iodine-131?

Back

8 days.

Front

If you start with 200 grams of a radioactive isotope with a half-life of 10 years, how much will remain after 30 years?

Back

50 grams.

Front

If you have 80 grams of a radioactive isotope with a half-life of 5 years, how much will remain after 15 years?

Back

10 grams.

Front

What is the half-life of an isotope that decays to 25% of its original amount in 20 years?

Back

10 years.

Front

If 10 mg of iodine-131 is given to a patient, how much is left after 24 days?

Back

1.25 mg.

Front

How many half-lives are in 40 years if the half-life is 10 years?

Back

4 half-lives.

Front

What is the remaining amount of a 100 mg sample after 3 half-lives?

Back

12.5 mg.

Front

If a radioactive isotope has a half-life of 3 days, how much of a 64 mg sample remains after 9 days?

Back

8 mg.

Front

What happens to the amount of a radioactive substance over time?

Back

It decreases exponentially.