Half-life Checkup Review

After the third half-life, how much of the sample is left?

• 1/2

• 1/3

• 1/16

• 1/8

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NGSS.HS-PS1-8

What is Half-life?

• The amount of time it takes for some of the nuclei in a sample of the isotope to decay
• The amount of time it takes for half the electrons in a sample of the isotope to decay
• The amount of time it takes for half the nuclei in a sample of the isotope to decay
• the amount of time it takes to double the nuclei in a sample of the isotope to decay

Tags

NGSS.HS-PS1-8

What is the half-life of iodine-131?

• 32 days
• 8 days
• 16 days
• 24 days

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NGSS.HS-PS1-8

The % of the parent isotope remaining after 1 Half Life.

• 50%

• 25%

• 12.5%

• 6.25%

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NGSS.HS-PS1-8

The % of the parent isotope remaining after 2 Half Lives.

• 50%

• 25%

• 12.5%

• 6.25%

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NGSS.HS-PS1-8

What is the Half life of this isotope?

• 5 seconds

• 10 seconds

• 15 seconds

• 20 seconds

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NGSS.HS-PS1-8

The % of the parent isotope remaining after 3 Half Lives.

• 50%

• 25%

• 12.5%

• 6.25%

Tags

NGSS.HS-PS1-8

Isotopes have different numbers of

• protons.

• neutrons.

• electrons.

• nuclei.

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NGSS.HS-PS1-8

Half life (in radioactivity) is the amount of time it takes for half of a radioactive sample to

• split.

• combine.

• decay.

• become parent material.

Tags

NGSS.HS-PS1-8

You have 100 grams of radioactive C-14. The half life of C-14 is 5730 years.

How many grams are left after 2 half lives?

• 100 grams

• 25 grams

• 50 grams

• 14 grams