Half-Life

Front

What is Half-life?

Back

The amount of time it takes for half the nuclei in a sample of the isotope to decay.

Front

If the half-life of strontium-90 is 25 years, how much will remain after 100 years if the initial amount is 4.0 g?

Back

0.25g

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

What is the Half Life of an isotope that decays to half its amount in 3 days?

Back

3 days

Front

If 10 mg of iodine-131 is given to a patient, how much is left after 24 days? The half-life of iodine-131 is 8 days.

Back

1.25mg

Front

Define radioactive decay.

Back

The process by which an unstable atomic nucleus loses energy by emitting radiation.

Front

What is the formula to 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

How many half-lives are in 100 years if the half-life of a substance is 25 years?

Back

4 half-lives.

Front

What happens to the amount of a radioactive substance after each half-life?

Back

It reduces to half of its previous amount.

Front

If a substance has a half-life of 5 days, how much of a 40 g sample remains after 15 days?

Back

5 g.