Question

Uranium-238 with a half-life of 4.5 billion years decays in a multi-step process.
a) Show that the following series of decays will result in the formation of lead-206.
α β- β- α α α α β- α β- α β- α β-.

b) Suppose that a piece of an asteroid has a lead-206 atoms : uranium-238 atoms ratio of 1:1. Assuming that all of the lead-206 in the asteroid came from the uranium-238, how old is the asteroid?

c) If some lead-206 was already present in the asteroid when it was formed, is the asteroid younger than or older than your answer for part (b)? Defend your answer.

Answer 1