Half Life Calculations

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

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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

You have 100 grams of radioactive C-14. The half life of C-14 is 5730 years. 
How many grams are left after 1 half life? 

• 100 grams

• 25 grams

• 2 grams

• 50 grams

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NGSS.HS-PS1-8

Which diagram best represents the percentage of this radioactive isotope sample that will remain after 2 half-lives?

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NGSS.HS-PS1-8

The Half Life of Californium 252 is 5 years.

• TRUE

• FALSE

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NGSS.HS-PS1-8

How long would it take for an element with a half-life of 100 years to reach 5 half-lives?

• 50

• 500

• 5000

• 5

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NGSS.HS-PS1-8

An Isotope of Cesium-137 has a half life of 30 years. If 1.0 g of Cesium-137 disintegrates over a period of 90 years, how many grams of Cesium-137 would remain? 

• .125 grams

• .5 grams

• 15 grams

• 45 grams

Tags

NGSS.HS-PS1-8

Actinium-226 has a half life of 29 hours. If 100 milligrams of Actinium disintegrate over a period of 58 hours, how many milligrams of Actinium will remain?

• 100 mg

• 50 mg

• 25 mg

• 58 mg

Tags

NGSS.HS-PS1-8

Selenium-83 has a half life of 25 minutes. How many minutes would it take for a 20 milligram sample to decay and only have 1.25 milligrams of it remaining?

• 25 minutes

• 50 minutes

• 75 minutes 

• 100 minutes

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

Tags

NGSS.HS-PS1-8