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

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 8 days, how much of a 10 mg sample remains after 24 days?

Back

1.25 mg

Front

What is the half-life of iodine-131?

Back

The half-life of iodine-131 is 8 days.

Front

If you start with 32 parent isotopes, how many half-lives have occurred if there are still 32 parent isotopes left?

Back

0 half-lives have occurred.

Front

If you start with 32 parent isotopes and end up with 16 parent isotopes, how many half-lives have occurred?

Back

1 half-life has occurred.

Front

What type of decay is characterized by the emission of an alpha particle?

Back

Alpha decay.

Front

What is the half-life of strontium-90?

Back

The half-life of strontium-90 is 25 years.

Front

How much strontium-90 remains after 100 years if the initial amount is 4.0 g?

Back

0.25 g remains.

Front

What happens to the number of parent isotopes after one half-life?

Back

The number of parent isotopes is reduced by half.