Absolute Dating and Geologic Time Scale

The graph shows the percentages of the radioactive isotope carbon-14 (14C) and its disintegration product produced during four half-lives of radioactive decay.

Which disintegration product is represented on the graph?

• Pb-206

• Sr-87

• Ar-40

• N-14

Tags

NGSS.HS-PS1-8

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

Tags

NGSS.HS-PS1-8

How many half-lives have passed if a sample contains 25% of its original carbon-14?

• 1 half-life

• 2 half-lives

• 3 half-lives

• 4 half-lives

During which geologic period did humans first appear on Earth?

• Quaternary

• Paleogene

• Triassic

• Permian

During which geologic period did plants and animals first appear in land environments?

• Devonian

• Cambrian

• Ordovician

• Silurian

Tags

NGSS.HS-LS4-2

The graph below shows the rate of decay of a radioactive isotope through two half-lives. Each box shows the ratio of atoms of the radioactive isotope to atoms of the disintegration product. The box at two half-lives has been left blank.

Which box best represents the ratio of these atoms at two half-lives?

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Tags

NGSS.HS-PS1-8

Which sequence shows the correct order of Earth’s geologic time intervals from oldest to youngest?

• Archean →
  Mesozoic →
  Cenozoic → Paleozoic → Proterozoic

• Archean → Proterozoic → Paleozoic → Mesozoic →
  Cenozoic

• Cenozoic →
  Mesozoic → Paleozoic → Proterozoic → Archean

• Cenozoic → Paleozoic →
  Archean →
  Mesozoic → Proterozoic

Tags

NGSS.MS-ESS1-4

Approximately 2.2 billion years ago, which gas was first added in large amounts to Earth's atmosphere from life-forms that evolved in the oceans?

• Hydrogen
• Nitrogen
• Carbon dioxide
• Oxygen

Based on fossil evidence, which pie graph best shows the percentage of time that humans have existed on Earth since the time of Earth's origin?

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Tags

NGSS.MS-LS4-1

Geologic history is divided into eras, periods, and epochs based on the

• type of rock deposited at different times throughout history

• half-life of radioactive isotopes found in rocks

• inferred movements of Earth's landmasses

• fossil evidence found in bedrock