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

If you start with 100 grams of a substance, how much will remain after one half-life?

Back

50 grams.

Front

What percentage of a radioactive isotope remains after one half-life?

Back

50%.

Front

What percentage of a radioactive isotope remains after two half-lives?

Back

25%.

Front

What is the half-life of C-14?

Back

5730 years.

Front

If the half-life of an isotope is 3 days, how much of a 100 gram sample remains after 6 days?

Back

25 grams.

Front

What is the half-life of iodine-131?

Back

8 days.

Front

How do you calculate the remaining amount of a radioactive substance after multiple half-lives?

Back

Use the formula: Remaining amount = Initial amount × (1/2)^(number of half-lives).

Front

What is the remaining percentage of a parent isotope after three half-lives?

Back

12.5%.

Front

If a substance has a half-life of 10 days, how much of a 200 gram sample remains after 20 days?

Back

50 grams.