The half-life for a 100-gram sample of radioactive element X is 5 days. How much of element X remains after 10 days have passed?

• 25 grams

• 50 grams

• 75 grams

• 100 grams

How many half-lives does it take a radioactive substance to decay until only one-eighth (1/8) of the original substance remains.

• 2

• 3

• 6

• 8

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NGSS.HS-PS1-8

The diagram shows a nuclear reaction. Which type of reaction is shown in the diagram?

• Fusion, because the reaction released energy.

• Fission, because the reaction absorbed energy

• Fusion, because the reaction formed lighter nuclei.

• Fission, because the reaction formed heavier nuclei.

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NGSS.HS-PS1-8

Which statement best describes what happens in a fission reaction?

• Light nuclei form into heavier nuclei.

• Heavy nuclei split into lighter nuclei.

• Energy is released, and less stable elements are formed.

• Energy is absorbed, and more stable elements are formed.

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NGSS.HS-PS1-8

Which change takes place in a nuclear fusion reaction?

• Covalent bonds are converted to ionic bonds.

• Ionic bonds are converted to covalent bonds.

• Matter is converted to energy.

• Energy is converted to matter.

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NGSS.HS-ESS1-1

NGSS.HS-PS1-8

What generates the energy produced when small, light atoms are combined into heavier ones?

• Fusion reactions

• Chemical reactions

• Fission reactions

• Nuclear chain reactions

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NGSS.HS-ESS1-1

NGSS.HS-ESS1-3

NGSS.HS-PS1-8

Sodium-24 has a half-life of approximately 15 hours. If only one-eighth of the sodium-24 remains, about how much time has passed.

• 15 hours

• 30 hours

• 45 hours

• 60 hours

Cerium-143 is a radioactive isotope that decays to produce praseodymium-143. The half-life for cerium-143 is approximately 33 hours. If 6.25 g cerium-143 remains from a 100-g sample, which statement is true? Select all that apply.

• Cerium-143 decayed for 132 hours.

• Cerium-143 decayed for 166 hours.

• Two half-lives have passed.

• Three half-lives have passed.

• Four half-lives have passed.

Radioactive isotopes

• have very unstable nuclei.

• have the most stable nuclei.

• have more electrons than protons.

• have emitted all of their neutrons.

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NGSS.HS-PS1-8

The graph shows the radioactive decay of a bone that is found to contain 1/8 of the carbon-14 found in living animals today.

• 5,790 years

• 11,460 years

• 17,190 years

• 22,920 years

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NGSS.HS-PS1-8