6.3 Half-Life

Front

What is the term used to describe the time it takes for a radioactive isotope to decay to half its original mass?

Back

Half-life

Front

If the half-life of a substance is 10 years, how much of a 100 g sample remains after 20 years?

Back

25 g (after 2 half-lives)

Front

What is the half-life of uranium-232?

Back

70 years

Front

How many half-lives are required for a substance to decay from 80 g to 10 g?

Back

4 half-lives

Front

What is the remaining mass of a 200 g sample of C-14 after 2 half-lives?

Back

50 g

Front

If a radioactive isotope has a half-life of 5 years, how much of a 64 g sample remains after 15 years?

Back

8 g (after 3 half-lives)

Front

What is the half-life of C-14?

Back

5730 years

Front

If you start with 1,000 atoms of a radioactive isotope with a half-life of 1 year, how many atoms will remain after 3 years?

Back

125 atoms (after 3 half-lives)

Front

What is nuclear fusion?

Back

A process where two light atomic nuclei combine to form a heavier nucleus, releasing energy.

Front

How many U-238 atoms will be left after one half-life if you start with 50,000 atoms?

Back

25,000 atoms