Geological Tour

What is Half-life?

• The amount of time it takes for some of the nuclei in a sample of the isotope to decay
• The amount of time it takes for half the electrons in a sample of the isotope to decay
• The amount of time it takes for half the nuclei in a sample of the isotope to decay
• the amount of time it takes to double the nuclei in a sample of the isotope to decay

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

Which radioactive element is used to determine the absolute age of late Pleistocene animal remains?

• rubidium-87

• uranium-238

• potassium-40

• carbon-14

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

• 50%

• 25%

• 12.5%

• 6.25%

Radiometric dating is possible because the rates of decay of radioactive isotopes _____.

• change over time
• change from place to place
• are constant
• vary widely

The time it takes for 50% of the nuclei in a radioactive sample to decay to its stable isotope is called _____.

• the daughter product
• geologic time
• the half-life
• the half-time

Scientists use radioactive decay to measure...

• relative time
• absolute time
• half-lives
• time of day

The length of time required for half of the radioactive atoms in a sample to decay is its...

• era
• age
• half-life
• eon

According to the law of superposition, the oldest fossils are found 

• At the top of the rock layers
• Near the bottom of the rock layers
• In the middle of the rock layers
• Somewhat near the surface

Which type of dating method can be used on rock layers by applying the Law of Superposition?

• relative dating
• absolute dating
• radioactive dating
• radiometric dating