Combination or Synthesis Reactions: A reaction in which a single product is formed from multiple reactants
A) Fe2O3(s) + 3CO(g) -> 2Fe(s) + 3CO2(g)
B) 2H2(g) + O2(g) -> 2H2O(l)
C) 2HgO(s) -> 2Hg(l) + O2(g)
D) NH3(g) + HCl(g) -> NH4Cl(s)