Cosmic Combination!
The best current measurements of the percentage abundances of different kind of nuclei by mass in the Universe are:
hydrogen ---- 73
helium ---- 25
everything else ---- 2
After the annihilation of matter with antimatter, the Universe was hot enough for electrons to combine with protons to form neutrons. Neutrons have a half-life of about 11 minutes. The standard model uses knowledge of the behavior of subatomic particles to predict that in the next three minutes there was a stable ratio of about two neutrons for every 14 protons in the universe. These would then combine to form as much helium as possible.
a)
How many helium nuclei would be formed from these 16 nucleons?
b)
How many protons would be left?
c)
What would be percentage of helium mass to total mass for this sample?
d)
What percentage by mass should be hydrogen?
N.B: Please choose the correct choice in the order a) , b) , c) , d)
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