Half Life Calculations

If a radioactive isotope has a half-life of 10 years, how many years will it take for the isotope to decay to 1/8 of its original amount?

• 20 years

• 30 years

• 40 years

• 50 years

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The half-life of Bi-212 is 1 hour.  Suppose you put a 50.0 g sample of Bi-212 in your

locker before going to first period. How much would remain at the end of third period after 3 hours?

• 6.25

• 12.5

• 25

• 50

How much of a 500g sample of potassium-42 is left after 20 hours if the half life of potassium-42 is 5 hours?

• 30

• 31.25

• 250

• 125

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According to the graph how long is the half life of this substance?

• 10 years

• 25 years

• 50 years

• 100 years

What is the role of half-life in nuclear energy production?

• It determines the amount of energy produced in a nuclear reaction.

• It is used to calculate the safety measures needed in a nuclear plant.

• It helps in determining the age of archaeological finds.

• It is used to estimate the time a radioactive material can be used as a fuel source.

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Why is the concept of half-life important in the disposal of nuclear waste?

• It helps in converting nuclear waste into non-radioactive materials.

• It determines how long nuclear waste will remain hazardous.

• It increases the decay rate of nuclear waste.

• It decreases the amount of nuclear waste produced.

What happens to the radioactivity of a material after one half-life?

• It doubles

• It remains the same

• It is reduced by half

• It is completely gone

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What is the definition of half-life?

• The time it takes for a substance to fully decay

• The time it takes for half of the radioactive atoms in a sample to decay

• The time it takes for a substance to double in mass

• The time it takes for a substance to lose all of its radioactive properties

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If one-fourth of the carbon-14 is remaining then how many half-lives have passed?

• 1

• 2

• 3

• 4

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

• 1/2

• 1/3

• 1/16

• 1/8

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