In the following balanced redox reactions, identify the species (ion or molecule) that has been oxidized and the species that has been reduced. If the species contains more than one element, indicate which element (or elements) has undergone a change in oxidation state, and the magnitude of the change. a. Cr2O72(aq)+3C2O42(aq)+14H+(aq)2Cr3+(aq)+6CO2(g)+7H2O b. Cu2S(s)+8HNO3(aq)+4H+(aq)2Cu2+(aq)+SO2(g)+8NO2(g)+6H2O c. 2F2(g)+2OH(aq)OF2(aq)+2F(aq)+H2O