The following chemical reactions have helped to shape Earth's crust: a. SiO2(s)+2Fe(s)+O2(g)Fe2SiO4(s) b. 4FeO(s)+O2(g)+6H2O(I) 4Fe(OH)3(s) 1. In reaction a, the element is oxidized, and the element is reduced. The oxidizing agent is , and the reducing agent is (Please enter chemical formulas). 2. In reaction b, the element is oxidized, and the element is reduced. The oxidizing agent is , and the reducing agent is (Please enter chemical formulas)