Half-Life (Level-Up Your Learning!)

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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? Round to two decimal points. NO UNITS

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Os-182 has a half-life of 21.5 hours. How many grams of a 10.0 gram sample would have decayed after exactly three half-lives? N_t=N_o(0.5)^(T/t_1/2) Use the correct number of significant figures. Include units in your answer.

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After two half-lives, what percentage of the radioactive element will remain within the igneous rock?

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if we start with 400 atoms of radioactive substance, how many would remain after one half life?

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If 10 mg of iodine 131 is given to a patient, how much is left after 24 days? The half-life of iodine-131 is 8 days. Round to two decimal points. NO UNITS NEEDED

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Sodium-24 has a half-life of 15 hours. How much sodium-24 will remain in an 18g sample after 60 hours?

Do not round your answer.

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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? Round to two decimal points.

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Humber of half-lives at 75

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You collected a sample of a rock and it had 25% remaining of a radioactive element with a half life of 60 years. How old was that rock sample?

Multiple Choice

After how many half-lives would you only have 12.5% of the original isotope left?

• 1

• 2

• 3

• 4

Multiple Choice

What percentage of the original isotope is left after 2 half-lives?

• 100%

• 75%

• 50%

• 25%

Multiple Choice

How many half-lives have passed if 12.5% ¹⁴C remains?

• 1 Half-life

• 2 Half-lives

• 3 Half-lives

• 4 Half-lives

Multiple Choice

How many grams of Carbon-14 will remain after 17,100 years?

• 32 g

• 16 g

• 8 g

• 4 g