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

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

Back

3 days.

Front

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

Back

1.25 mg.

Front

You have 100 grams of radioactive C-14. How many grams are left after 1 half life (5730 years)?

Back

50 grams.

Front

Why is radioactive carbon-14 useful in determining the absolute age of geologic samples?

Back

Because radioactive isotopes decay at a regular rate.

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 the half-life of a substance is 10 years, how much of a 200 mg sample remains after 20 years?

Back

50 mg.

Front

What is the formula to calculate the remaining quantity of a substance after a certain number of half-lives?

Back

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

Front

If a substance has a half-life of 5 years, how many half-lives are in 15 years?

Back

3 half-lives.

Front

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

Back

It helps determine the age of materials by measuring the remaining radioactive isotopes.