5.5 Mastery Check v2: 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

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

Back

0.25 g.

Front

What is the half-life of barium-122?

Back

2 minutes.

Front

How much barium-122 will be left after 10 minutes if the initial amount is 80 g?

Back

2.5 g.

Front

If one-fourth of carbon-14 is remaining, how many half-lives have passed?

Back

2 half-lives.

Front

What is released when nuclei decay?

Back

Massive amounts of energy.

Front

What is the formula to find the remaining mass after multiple half-lives?

Back

Remaining mass = Initial mass × (1/2)^(n), where n is the number of half-lives.

Front

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

Back

It decreases exponentially.