Absolute Dating

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

What element is usually used to date fossils?

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

How old is the Earth?

• 4.6 billion years
• 1.4 billion years
• 4.6 million years
• 6000 years

The original element that undergoes radioactive decay is known as the...

• daughter element
• half-life
• parent element
• carbon-14

If 10 mg of iodine 131 is given to a patient, how much is left after 24 days? The half-life of iodine-131 is 8 days.

• 1.25mg
• 1.25g
• 10g
• 10mg

The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?

• 3.0g
• 0.25mg
• 0.3g
• 0.25g