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

Back

50g

Front

What percentage of a parent isotope remains after 1 half-life?

Back

50%.

Front

What percentage of a parent isotope remains after 2 half-lives?

Back

25%.

Front

What is the half-life of strontium-90?

Back

25 years.

Front

If you start with 4.0g of strontium-90, how much will remain after 100 years?

Back

0.25g.

Front

How many half-lives are in 100 years if the half-life is 25 years?

Back

4 half-lives.

Front

If you have 50,000 atoms of uranium-238, how many will remain after 4.5 billion years?

Back

25,000 atoms.

Front

What is the half-life of an isotope if 12.5% of the parent isotope remains?

Back

It has gone through 3 half-lives.

Front

If the half-life of a substance is 5 days, how much of a 40g sample remains after 15 days?

Back

5g.