remain after three half-lives?
b. An isotope of technetium, technetium-99, has a half-life of 6 hours. A hospital has a sample
which contains 36 mg of technetium-99. Calculate how much technetium-99 will be in this
sample after 12 hours.
c. Plutonium-238 is used in spacecraft to provide heat to power generators. One of these
generators contains 925 g of plutonium-238 when it is manufactured. Given that the half-life
of plutonium-238 has a half-life of 87.7 years, calculate the mass of plutonium-238
remaining after 200.0 years.