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