Half Life Decay and Nuclear Reaction Equations

The technetium-99 isotope has a half-life of 6.0 hours. If 100.0 mg were injected into a patient, how much remains after 18 hours?

• 33.0 mg

• 12.5 mg

• .33 mg

• 15.8 mg

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NGSS.HS-PS1-8

The half life of Thorium-234 is 24 days. What fraction of the element remains after 96 days?

• 1/2

• 1/4

• 1/8

• 1/16

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NGSS.HS-PS1-8

Barium-122 has a half-life of 2 minutes. A fresh sample weighing 80 g was obtained. If it takes 10 minutes to set up an experiment using barium-122, how much barium-122 will be left when the experiment begins?

• 0.25g
• 2.5g
• 25g
• 80g

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NGSS.HS-PS1-8

The half-life of Fermium-253 is 3 days. That means a 200 g sample of Fermium-253 will decay down to _______g after 3 days.

• 126

• 6

• 400

• 100

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NGSS.HS-PS1-8

The half-life of Carbon-10 is 19 seconds. That means an 800 g sample of Carbon-10 will decay down to 50 g after _______ seconds.

• 57

• 76

• 95

• 38

How much of a 20 gram sample of sodium-24 remains after decaying 45 hours if the half-life of sodium is 15 hours?

• 2.5 grams

• 3 grams

• 6.7 grams

• 20 grams

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NGSS.HS-PS1-8

How long would it take for a 100 gram sample of Titanium-51 to decay to 3.125 grams of radioactive material if the half-life of Titanium-51 is 6 minutes?

• 6 minutes

• 24 minutes

• 30 minutes

• 60 minutes

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NGSS.HS-PS1-8

If a patient is given a 2.0 gram sample of Iodine-131 during therapy, how much Iodine-131 remains in his body after 48.6 days? The half-life of Iodine-131 is 8.1 days?

• .03125 grams

• .0625 grams

• 1 gram

• 128 grams

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NGSS.HS-PS1-8

A sample of 56 grams of carbon-14 undergoes 3 half-lives. How much remains?

• 3 grams

• 7 grams

• 18.7 grams

• 716.25 grams

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NGSS.HS-PS1-8

How long does it take 56.0 grams of carbon-14 to decay to 7.0 grams? The half-life of carbon-14 is 5730 years.

• 42 years

• 1910 years

• 5730 years

• 17190 years

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NGSS.HS-PS1-8