10.7 Exercise 16

A nuclear physicist finds $1.0 \mu g$ of $^{236} \text{U}$ in a piece of uranium ore (T_1/2 = $2.348 \times 10^{7} \text{y}$). (a) Use the decay law to determine how much $^{236} \text{U}$ would had to have been on Earth when it formed $4.543 \times 10^{9} \text{y}$ ago for $1.0 \mu g$ to be left today. (b) What is unreasonable about this result? (c) How is this unreasonable result resolved?