10. Solving a chemistry problem

18. A sample of radioactive uranium weighing 100 g decays according to the scheme: 239U → 23.5 239Np → 2.35 days 239 Pu
(the half-lives are indicated above the arrow). Calculate the masses of neptunium and ratonium using:
1) 20 minutes;
2) 20 days after the start of decay.
Determine the maximum mass of neptunium that can be obtained from a given sample of uranium.