Nuclear Reactions and Half-Life

The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed?

• 100.0g

• 50.0g

• 12.5g

• 8.5g

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NGSS.HS-PS1-8

If the half-life of uranium-232 is 70 years, how many half-lives will it take for 10 g of it to be reduced to 1.25 g?

• half-life

• half-lives

• half-lives

• half-lives

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NGSS.HS-PS1-8

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

• 15%

• 12.5%

• 6.25%

• 3.125%

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

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NGSS.HS-PS1-8

Identify the half life of the substance shown in the graph.

• 4 days

• 8 days

• 12 days

• 16 days

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NGSS.HS-PS1-8

A 50.0 g sample of N - 16 decays to 12.5 g in 14.4 seconds. What is it's half - life?

• 14.4 sec

• 7.2 sec

• 3.6 sec

• 1.8 sec

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NGSS.HS-PS1-8

The time required for half of the parent isotope to decay into daughter isotopes.

• Absolute Age

• Relative Age

• Fossil

• Half-life

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NGSS.HS-PS1-8

The amount of time it takes for half of the particles of an element to decay is called:

• Absolute Age

• Half-Life

• Radioactivity

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NGSS.HS-PS1-8

Suppose you extract one gram of carbon from an ancient wooden hammer handle. You find that your ancient gram of carbon is half as radioactive as a gram of carbon extracted from a tree branch that was cut today. The half-life of C-14 is 5,730 years. Assuming that today’s ratio of C-14 to C-12 is the same as when the hammer was made, how old would you estimate is the hammer?

• 1,432.5 years old

• 2,865 years old

• 5,730 years old

• 11,460 years old

What is the half-life of a radioactive element?

• How old it is when it is middle aged

• The time it takes for half of the atoms to decay

• The time it takes for half of the atom to form

• How old it is when the Earth is middle aged

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NGSS.HS-PS1-8