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The table below shows the radioactive decay of carbon-14. Part of the table has been left blank.

After 22,800 years, approximately what percentage of the original carbon-14 remains?*

The graph below represents the decay of a radioactive isotope into a stable disintegration product.

Which remains could be dated using this radioactive isotope?*

Base your answers to questions 3 on the table below and on your knowledge of Earth science. The table below lists the half-lives for fi ve radioactive isotopes.

Which radioactive isotope has a half-life closest to the half-life of the radioactive isotope rubidium-87?*

A bar graph of the radioactive decay of carbon-14 is shown below.

The solid black sections of the bars on the graph represent the percentages of*

A fossil formed 11,400 years ago. Which percentage of the original amount of carbon-14 remains in the fossil?*

How old is a bone that has 12.5% of the original amount of radioactive carbon-14 remaining?*

The image below shows a spear point embedded in part of a mastodonâ€™s rib bone, found near Seattle, Washington.

Scientists infer that early North American humans hunted the mastodon. Carbon-14 dating of the rib bone indicates that 2.4 half-lives have passed since the mastodon was killed. Approximately how many years ago did the mastodon die?*

Base your answers to questions 8 on the table below and on your knowledge of Earth science. The table shows the disintegration products and half-lives of five commonly used radioactive isotopes.

Which graph below represents the amount of potassium-40 and the amount of argon-40 and calcium-40 over four half-lives?*

Which radioactive isotope is most often used when determining the age of fossil bones found in sediments deposited during the Holocene Epoch?*

Base your answers to questions 10 on the data table and information below and on your knowledge of Earth science. The data table shows the radioactive decay of carbon-14 and the age of fossil remains, in years (y). Part of the table has been left blank.

Identify the decay product when carbon-14 undergoes radioactive disintegration. [1]*

Base your answers to questions 11 on the graph below and on your knowledge of Earth science. The graph shows the rate of decay of the radioactive isotope carbon-14 (^{14}C).

Identify the decay product formed by the disintegration of carbon-14. [1]*

Base your answers to questions 12 on the information below and on your knowledge of Earth science.

A scientist found the bone of a mastodont. In the lab, the scientist found that 12.5% of the original radioactive C-14 still remained in the bone.

Explain why ^{14}C was used to date the mastodont bone. [1]*

Base your answers to questions 13 on the diagram in image provided and on your knowledge of Earth science. The diagram represents a model of the radioactive decay of carbon-14. The white boxes represent radioactive carbon-14 remaining, and the black boxes represent the disintegration product after the fi rst half-life.

State the name of the disintegration product of carbon-14. [1]*

Base your answers to questions 14 on the diagrams below and on your knowledge of Earth science. The diagrams represent a model of the disintegration of a sample of the radioactive isotope carbon-14 (^{14}C).

Identify the stable disintegration product that is produced when carbon-14 decays. [1]*

Base your answers to questions 15 on the cross sections below and on your knowledge of Earth science. The cross sections represent three bedrock outcrops, 1, 2, and 3, found several kilometers apart.

X The geologic time period when each sedimentary rock layer formed is shown. The symbols ( , , , , and ) represent fossils of different types of organisms present in the rock layers.

Explain why the geologic age of these rock layers could not be accurately dated using carbon-14. [1]*