Geoscience QTR 2 2017 review

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.

• 1.25mg
• 1.25g
• 10g
• 10mg

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CCSS.HSF.LE.A.4

If the half-life of uranium-232 is 70 years, how many half-lives will it take for 10 g of it to be reduced to 1.25 g?

• 1 half-life
• 2 half-lives
• 3 half-lives
• 4 half-lives

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CCSS.HSF.LE.A.4

The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed?

• 100.0g
• 50.0g
• 12.5g
• 8.5g

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CCSS.HSF.LE.A.4

The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed?

• 100.0g
• 50.0g
• 12.5g
• 8.5g

Tags

CCSS.HSF.LE.A.4

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?

• 3.0g
• 0.25mg
• 0.3g
• 0.25g

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CCSS.HSF.LE.A.4

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

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

• 1/2
• 1/3
• 1/16
• 1/8

After 4 half-lives, 1g of a sample of Krypton-85 remains unchanged.  What was the original mass of the sample?

• 16g
• 32g
• 0.0625g
• 4g

An isotope of an element has the same number of _________, but a different number of _________.

• Protons, electrons
• Protons, neutrons
• Electrons, neutrons

After a period of 140 days, one-fourth of the original amount of the element remains. The half-life of the isotope is ____.

• 70 days
• 78 days
• 84 days
• None of the above