Half-Life

After 22,800 years, approximately what percentage of the original carbon-14 remains?

• 15%

• 12.5%

• 6.25%

• 3.125%

Radioactive carbon-14 is often useful in determining the absolute age of geologic samples because radioactive isotopes

• decay at a regular rate

• become less stable during decay

• remain unchanged over time

• stabilize after four half-lives

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NGSS.HS-PS1-8

When nuclei decay, massive amounts of __________ is released.

• energy

• jello

• protons

• neutrons

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NGSS.HS-PS1-8

________________ is the time it takes for half of the radioactive atoms in an element to decay.

• Half-life

• Radiation

• Relative age

• Full-life

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NGSS.HS-PS1-8

The graph shows the radioactive decay of a 50-gram sample of a radioactive isotope. 
According to the graph, what is the half-life of this isotope? 

• 100 years

• 150 years

• 200 years

• 300 years

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NGSS.HS-PS1-8

You find a rock sample with radioactive atoms present.  If 12.5% of the original radioactive atoms were present, how many half-lives has the rock been around for? (Hint, at Half-Life = 0, you start with 100%)

• zero

• 1

• 2

• 3

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NGSS.HS-PS1-8

You find a rock sample with radioactive atoms present.  If 25% of the original radioactive atoms were present, how many half-lives has the rock been around for? (Hint, at Half-Life = 0, you start with 100%)

• zero

• 1

• 2

• 3

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NGSS.HS-PS1-8

Using ESRT (A) [Radioactive Decay Data], what is the half-life in standard notation of carbon-14?

• 5,700 years

• 57,000 years

• 570,000 years

• 5,700,000 years

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NGSS.HS-PS1-8

Using ESRT (A) [Radioactive Decay Data], what is the half-life in standard notation of Uranium-238?

• 4,500 years

• 450,000 years

• 4,500,000 years

• 4,500,000,000 years

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NGSS.HS-PS1-8

Which radioactive isotope takes the greatest amount of time to undergo radioactive decay? 

• Carbon-14

• Potassium-40

• Uranium-238

• Rubidium-87

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NGSS.HS-PS1-8