Answer
Please see the work below.
Work Step by Step
We know that the isotopes that begin with each of the natural radioactive decay series are uranium -238, uranium-235 and thorium-232.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.