Technetium-99m is a radioactive isotope commonly used in medicine as a radioactive tracer. A radioactive tracer is an isotope injected into the body to help create images for diagnosis of health problems. Technetium-99m has a half-life of 6 hours. If a patient receives a dose of technetium-99m one morning, about what percentage of the technetium-99m will be left in the patient's body 12 hours later?
a
12.5%
b
6.25%
c
25.0%
d
93.8%
The half-life of technetium-99m is 6 hours. This means that after 6 hours, half of the technetium-99m will have decayed, and after 12 hours, another half of the remaining technetium-99m will have decayed.
So, after 12 hours, only 25% (half of the remaining half) of the technetium-99m will be left in the patient's body.
Therefore, the answer is c) 25.0%.