Answer:
The half-life of plutonium-238 is 87.7 years.
What percentage of the atoms in a sample of plutonium-238 will remain radioactive after 263.1 years?
12.5
%
What percentage of the atoms in the same sample of plutonium-238 will have changed to a stable isotope after 263.1 years?
87.5
%
Step-by-step explanation: