Absolute vs. Relative Dating

Why are isotopes with short half-lives not useful for dating very old rocks?

• because not enough of the parent isotope remains to measure accurately
• because not enough of the daughter product has formed to be detectable
• because neither the parent isotope nor the daughter product will be detectable
• because very old rocks would never have contained these isotopes

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

How does absolute age differ from relative age?

• only absolute dating indicates which rock is older than another
• only absolute dating finds the age in years
• only relative dating finds the age in years

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

If the half-life of a radioactive group of atoms is 100 years, then how old is the rock if there have been two half-lives?

• 25 years
• 200 years
• 400 years
• 800 years

Tags

CCSS.HSF.LE.A.4

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 rock layer in the diagram seems to be the oldest?}

• F
• E
• B
• A

According to the law of superposition, which layer is the youngest?

• A
• B
• C