Intro U5 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 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 2.4 minutes, how much of a 100g sample remains after 7.2 minutes?

Back

12.5g.

Front

What fraction of a sample remains after 3 half-lives?

Back

1/8 of the original sample.

Front

If a radioactive isotope has a half-life of 6 hours, how much of a 100mg sample remains after 18 hours?

Back

12.5mg.

Front

What is the half-life of iodine-131?

Back

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

Front

How much of a 1.00g sample remains after 1 hour if the half-life is 20 minutes?

Back

0.125g.

Front

What is the formula to determine the number of half-lives that have passed?

Back

Number of half-lives = Total time elapsed / Half-life duration.

Front

If a sample has a half-life of 10 days, how much of a 200g sample remains after 30 days?

Back

25g.

Front

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

Back

Half-life helps predict how long it will take for a substance to decay to a certain level.