When the earth was forming the materials sank into the core and the lighter materials rose toward the surface.

Dense materials sank into the core and the lighter materials rose toward the surface.

answer:

the reaction is type of combination reaction.

explanation:

on the product side, there are 2 molecules of bonded to fe   which means one atom of fe are combined two molecules of . so, balanced chemical equation becomes :

this reaction follows the reaction type of combination reaction. a combination reaction is defined as chemical reaction in which reactants combines together to form a single product.