polleycolton3864 polleycolton3864 24-04-2024 Chemistry Answered A 228Th source is labeled 4.50 mCi, but its present activity is found to be 1.04 ✕ 107 Bq. (a) What is the present activity in mCi? (b) How long ago (in y) did it actually have a 4.50 mCi activity?