History of Life Quiz 2

Scientists estimate that the Earth is ......... years old

• 2 billion

• over 4 billion

• 400,000

• 4 million

What are two methods that scientists use to determine the age of rocks and fossils?

• Radioactive dating

• Microscopic dating

• Relative dating

• Isotopic dating

Elements that are isotopes......

• Have the same number of protons, but different numbers of neutrons

• Have the same number of neutrons, but different numbers of protons

• Have the same number of protons, but different numbers of electrons

• Are always radioactive

What is a half-life?

• The amount of time it takes for one-half of a sample of isotope to become radioactive

• The amount of time it takes for one-half of a sample of isotope to decay

• The amount of time it takes for a sample of isotope to completely disintegrate

• The amount of time it takes to measure one-half of a sample of isotope

If sample A has a greater ratio of carbon-14 to carbon-12 than sample B does, then....

• Sample A is older than sample B

• Sample A is newer than sample B

• Sample A and sample B are around the same age

• The amount of carbon-12 will continue to increase in sample A

Which of the following radioactive isotopes is used to date relatively new rocks and fossils, and why?

• Carbon-14 is used because it has a short half-life

• Carbon-14 is used because it has a long half-life

• Uranium-238 is used because it has a long half-life

• Uranium-238 is used because it has a short half-life

Which of the following isotopes is/are used to date relatively old rocks and fossils?

• Carbon-14

• Potassium-40

• Uranium-238

• Carbon-12