6.3 Half-Life

Front

What is half-life?

Back

Half-life is the time required for half of the quantity of a radioactive substance to decay or transform into another substance.

Front

How is half-life used in radioactive decay?

Back

Half-life is used to determine the time it takes for a radioactive substance to reduce to half its initial amount, which helps in understanding the stability and longevity of isotopes.

Front

If a substance has a half-life of 25 years, how much of a 100g sample remains after 25 years?

Back

50g

Front

If a substance has a half-life of 25 years, how much of a 100g sample remains after 50 years?

Back

25g

Front

If a substance has a half-life of 25 years, how much of a 100g sample remains after 75 years?

Back

12.5g

Front

What is the formula to calculate the remaining quantity after a certain number of half-lives?

Back

Remaining quantity = Initial quantity × (1/2)^(number of half-lives)

Front

How many half-lives are needed for a substance to decay from 80g to 10g if its half-life is 10 years?

Back

3 half-lives

Front

What is the half-life of iodine-131?

Back

8 days

Front

How much of a 250g sample would be left after 5 half-lives if the half-life is 10 years?

Back

7.81g

Front

If the half-life of uranium-232 is 70 years, how many half-lives will it take for 10 g to reduce to 1.25 g?

Back

3 half-lives