Answer:
1.5625
Explanation:
the half life of an isotope is the amount of time it takes for one half of the isotope to decay
28650 is 5 half lives (28650÷5730=5)
after one half life the mass will be 25 grams
after two half lives the mass will be 12.5 grams
after 3 half lives the mass will be 6.25 grams
after 4 half lives the mass will be 3.125 grams
after 5 half lives the mass will be 1.5625 grams
