Physical Science Half-Life

What is half-life?

• a type of radioactive substance

• how much time it takes for half the amount of a radioactive substance to decay

• an alpha particle

• the amount of time it takes for an atom to become radioactive

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NGSS.HS-PS1-8

If we start with 400 radioactive atoms, how many will remain radioactive after one half-life?

• 25

• 50

• 100

• 200

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NGSS.HS-PS1-8

If we start with 400 radioactive atoms, how many will remain radioactive after two half-lives?

• 25

• 50

• 100

• 200

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NGSS.HS-PS1-8

If we start with 400 radioactive atoms, how many will remain radioactive after three half-lives?

• 25

• 50

• 100

• 200

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NGSS.HS-PS1-8

If we start with 400 radioactive atoms, how many will remain radioactive after four half-lives?

• 25

• 50

• 100

• 200

If we start with 48 radioactive atoms, how many will remain radioactive after one half-life?

• 3

• 6

• 12

• 24

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NGSS.HS-PS1-8

If we start with 48 radioactive atoms, how many will remain radioactive after two half-lives?

• 3

• 6

• 12

• 24

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NGSS.HS-PS1-8

If we start with 48 radioactive atoms, how many will remain radioactive after three half-lives?

• 3

• 6

• 12

• 24

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NGSS.HS-PS1-8

If we start with 48 radioactive atoms, how many will remain radioactive after four half-lives?

• 3

• 6

• 12

• 24

Look at the graph on your sheet for questions 4, 5 & 6. What is the half-life of element A?

• 0.75 billion years

• 4.5 billion years

• 13 billion years

• more than 14 billion years

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NGSS.HS-PS1-8