Half Life Review

Front

What is half-life?

Back

The amount of time it takes for half the nuclei in a sample of the isotope to decay.

Front

If the half-life of an isotope is 25 years, how much of a 4.0 g sample remains after 100 years?

Back

0.25 g.

Front

What is the half-life of Polonium-218 if 0.0625 grams remains of a 2.00 gram original sample after 15 minutes?

Back

3 minutes.

Front

Actinium-226 has a half-life of 29 hours. How much of a 100 mg sample remains after 58 hours?

Back

25 mg.

Front

If the half-life of an element is 20 minutes, what % of the element remains after an hour?

Back

12.5%.

Front

Define half-life in the context of radioactive decay.

Back

Half-life is the time required for half of the radioactive nuclei in a sample to decay.

Front

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

Back

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

Front

What happens to the amount of a radioactive substance after each half-life?

Back

The amount of the substance decreases by half.

Front

If a substance has a half-life of 10 years, how much of a 40 g sample remains after 30 years?

Back

5 g.

Front

What is the significance of half-life in nuclear medicine?

Back

Half-life helps determine how long a radioactive substance remains effective for diagnosis or treatment.