Half Lives

A scientist finds a sample with a parent-to-daughter isotope ratio of 25:75. How many half-lives have passed?

• 1

• 4

• 3

• 2

If the half-life of a parent isotope is 2 billion years, and three half-lives have passed, how old is the sample?

• 2 billion years

• 4 billion years

• 6 billion years

• 8 billion years

Why is mathematical modeling important in radioactive dating?

• It allows scientists to observe isotopes directly in real time.

• It simplifies calculations for determining the age of a sample.

• It eliminates the need for experimental data.

• It helps measure the speed of chemical reactions.

Which isotope is most commonly used to date ancient biological samples?

• Carbon-14

• Uranium-238

• Potassium-40

• Thorium-232

Tags

NGSS.HS-PS1-8

What happens to the daughter isotope count as the parent isotope decays?

• It decreases

• It remains constant

• It fluctuates randomly

• It increases

Tags

NGSS.HS-PS1-8

How much of a 100.0g sample of Au - 198 is left after 8.10 days if its half - life is 2.70 days?

• 12.5 g

• 25.0 g

• 50.0 g

• 6.25 g

If 100 g of Au - 198 decays to 6.25 g in 10.8 days, what is the half - life of Au - 198?

• 1.8 days

• 2.7 days

• 3.6 days

• 5.4 days

Tags

NGSS.HS-PS1-8

The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?

• 3.0g

• 0.25mg

• 0.3g

• 0.25g

Tags

NGSS.HS-PS1-8

The % of the parent isotope remaining after 3 Half Lives.

• 50%

• 25%

• 12.5%

• 6.25%

Tags

NGSS.HS-PS1-8

The % of the parent isotope remaining after 1 Half Life.

• 50%

• 25%

• 12.5%

• 6.25%

Tags

NGSS.HS-PS1-8