Answer:
im going to say End Triassic is my favorite you can go on to wiki searching this and find all you are looking for.
something thats helps me is printing out he form and highlighting everything thats important and working from there
Explanation:
After 10 years, the isotope would have had two half lives. For each half life, half of the material reacts. Therefore, after one half life, 50% remains. Then, after a second, 25% remains. D is the correct answer.
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