Radioactive Decay Quiz

Iron-59 is used in medicine to diagnose blood circulation disorders. The half life of iron-59 is 44.5 days. How much of a 2.000 mg sample will remain after 133.5 days?

• 500 mg

• 250 mg

• 125 mg

• 62.5 mg

If Gallium-68 has a half life of 68.3 minutes, how much of a 10.0 mg sample is left after one half life? Two half lives? Three half lives?

• 1.25 mg

• 0.625 mg

• 68.5 mg

• 20 mg

If the passing of five half lives leaves 25.0 mg of a strontium-90 sample, how much was present at the beginning?

How much of a 1.0 g polonium-214 sample remains after 818 microseconds? The half life of polonium-214 is 163.7 microseconds.

The initial mass of a radioisotope is 10.0 g. If the radioisotope has a half life of 2.75 years, how much remains after four half lives?

The half life of tritium (3H) is 12.3 years. If 48.0 mg of tritium is released from a nuclear power plant during the course of a mishap, what mass of tritium will remain after 49.2 years? After 98.4 years?

Technetium-104 has a half life of 18.0 minutes. How much of a 165.0 g sample remains after 90.0 minutes?

Manganese-56 decays by beta emission and has a half life of 2.6 hours. How many half lives are there in 24 hours? How many mg of a 20.0 mg sample will remain after 5 half lives?