The element starts off as 100%. half of 100% is 50% and half of 50% is 25%. the element has emitted 2 times the half life which is 10,000 x 2 = 20,000
the fossil bone is 20,000 years old
The answer would be chromosomes
It provides an objective, standardized approach to conducting experiments and, in doing so, improves their results. By using a standardized approach in their investigations, scientists can feel confident that they will stick to the facts and limit the influence of personal, preconceived notions.
I'm not completely sure but I came up with Carbon dioxide, methane, water vapor, and nitrous oxide. I hope this is right and maybe helps you. Good luck!!
