Identify which of the following are oxidation-reduction reactions, and if they are, identify the oxidizing agent, the reducing agent, the substance being oxidized, and the substance being reduced.
CH4(g) + 2O2(g) --> CO2(g) + H2O(g)
Zn(s) + 2HCl(aq) --> ZnCl2(aq) + H2(g)
Cr2O7(2-) (aq) + 2OH(-) (aq) --> 2CrO42(-) (aq) + H2O(l)
HCl(g) + NH3(g) --> NH4Cl(s)
SiCl4(l) + 2H2O(l) --> 4HCl(aq) + SiO2(s)