Half Life Calculations Practice

An isotope of cesium 138 has a half-life of 30 years. If 1.00 g of cesium-138 disintegrates over a period of 90 years, how many grams of cesium-138 would remain?

Mathematical Equivalence

ON

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Level 2:After 4 half-life periods, 1.5 mg of a radioactive isotope remained. What was the mass of the original sample of the isotope?

You must use the chart to see if your answer is correct

• 6.0 mg

• 0.375 mg

• 3.0 mg

• 24 mg

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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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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

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

• 50%

• 25%

• 12.5%

• 6.25%

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The diagram shows 32 atoms.

16 of the Red are parent isotopes

16 of the Green are daughter isotopes

How many half-lives have occurred?

• 0

• 1

• 2

• 3

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What is the Half life of this isotope?

• 5 seconds

• 10 seconds

• 15 seconds

• 20 seconds

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What is the Half Life of this isotope?

• 3 days

• 5 days

• 8 days

• 10 days

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A 50.0 g sample of a radioactive element has a half-life of 40 years. How much mass will be left after 80 years?

• 50

• 25

• 12.5

• 6.25

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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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