Single Replacement: A reaction in which a (1) metallic element reacts with an ionic compound to replace the metal ion from the ionic compound as a metal element or a reaction in which a (2) nonmetal element reacts with an ionic compound to replace the nonmetal ion as a nonmetal element.
A) Fe2O3(s) + 3CO(g) -> 2Fe(s) + 3CO2(g)
B) 2H2(g) + O2(g) -> 2H2O(l)
C) 2HgO(s) -> 2Hg(l) + O2(g)
D) Zn(s) + CuSO4(aq) -> ZnSO4(aq) + Cu(s)