Absolute Dating

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

Relative Dating dates rocks __________
Absolute Dating dates rocks __________

• exact age; sequence
• sequence; exact age
• exact age; parent isotopes
• Laws; 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

What is the half life of carbon-14?

• 5730 years
• 4.5 billion years
• 2000 years
• 15 minutes

What element is usually used to date fossils?

• uranium-235
• carbon-14
• mercury-203
• thorium-234

What is the half-life of iodine-131?

• 32 days
• 8 days
• 16 days
• 24 days

How much radioactive material remains after 20 years?

• 100%

• 25%

• 6.25%

• 3.125%

What is the half-life of mercury-203?

• 50 years

• 50 days

• 50%

• 100 days

What percent of mercury-203 remains after 2 half-lifes?

• 50

• 25

• 75

• 12.5