Answer:
c) 2.5 g
Explanation:
half-life is the time it takes the radioactive isotope to decay to half of the intial sample.
so if the isotope decays to 2 half-lives, it will decay half the intial sample twice.
in the first half-life, the sample will decay from 10 g to 5 g. during the second half-life, the isotope will decay from 5 g to 2.5 g.
