Why is the era of nucleosynthesis so important in determining the chemical composition of the universe? a) all the elements except hydrogen were produced after the era of nucleosynthesis. b) we can observe spectra from this era to determine what the primordial mix of the elements was at the beginning of the universe. c) except for the small amount of matter produced later by stars, the chemical composition of the universe is the same now as at the end of the era of nucleosynthesis. d) we can study the processes that occurred during the era of nucleosynthesis to determine how most of the elements in the universe were created. e) by knowing how much matter was created during the era of nucleosynthesis, we can determine whether the universe is open or closed.

answer:

c) except for the small amount of matter produced later by stars, the chemical composition of the universe is the same now as at the end of the era of nucleosynthesis.

the first point, i am pretty sure.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-