Half Life Problems

Base your answer on on the graph below. The graph represents the decay of radioactive material X into a stable decay product.
Each of the objects below has different amounts remaining of the original radioactive material X. Which object is most likely the youngest?

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Tags

NGSS.HS-PS1-8

What is the mass of an original 5.60-gram sample of iron-53 that remains unchanged after 25.53 minutes?

• 0.35 g

• 0.70 g

• 1.40 g

• 2.80 g

Tags

NGSS.HS-PS1-8

What fraction of a Sr-90 sample remains unchanged after 87.3 years?

• 1/2

• 1/3

• 1/4

• 1/8

Tags

NGSS.HS-PS1-8

Which radioisotopes have the same decay mode and have half-lives greater than 1 hour?

• Au-198 and N-16

• Ca-37 and Fe-53

• I-131 and P-32

• Tc-99 and U-233

Tags

NGSS.HS-PS1-8

What is the total number of years that must pass before only 25.00 grams of an original 100.0-gram sample of C-14 remains unchanged?

•  2865 y

• 5730 y

• 11,460 y

• 17,190 y

Which nuclide has a half-life that is less than one minute?

• cesium-137

• francium-220

• phosphorus-32

• strontium-90

Tags

NGSS.HS-PS1-8

An original sample of the radioisotope fluorine-21 had a mass of 80.0 milligrams. Only 20.0 milligrams of this original sample remain unchanged after 8.32 seconds. What is the half-life of fluorine-21?

• 1.04s

• 2.08s

• 4.16s

• 8.3s

Tags

NGSS.HS-PS1-8

If of an original sample of krypton-74 remains unchanged after 34.5 minutes, what is the half-life of krypton-74?

• 11.5 min

• 23.0 min

• 34.5 min

• 46.0 min

Tags

NGSS.HS-PS1-8

What is the half-life and decay mode of Rn-222?

• 91 days and alpha decay

• 91 days and beta decay

• 3.82 days and alpha decay

• 3.82 days and beta decay

Tags

NGSS.HS-PS1-8

As a sample of the radioactive isotope ¹³¹I decays, its half-life

• decreases

• increases

• remains the same

Tags

NGSS.HS-PS1-8