Earth science help with all questions

  1. We start with 400 atoms of uranium-238. How many remain after 4.5 billion years?

After 9 billion years

After 13.5 billion years

Earth science help with all questions 1. We start with 400 atoms of uranium-238. How many remain after 4.5 billion years? After 9 billion years After 13.5 billi class=