19. (1 point) balance the following chemical equation: fe o₂ → fe₂o₃ what is the coefficient on fe, o₂ and fe₂o₃ *
1, 2, 3
4, 3, 2
1, 3, 1
2, 1, 1
20. (1 point) the law of conservation of mass lets us know that in every chemical equation you have to have the same number of on both sides of the equation. *
moles
coefficients
atoms of each element
molecules
21. (1 point) in order for the reaction: ca cuso₄ → cu caso₄ to occur, which of the following must be true? *
cu must be above ca on the activity series.
ca must be above cu on the activity series.
heat must be applied to the reaction.
none of the above

ch3 [ch2]14cooh

explanation:

i know insulin is primary but i dont know the others im sorry

explanation:

  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-