Balance each of the following equations. Classify each reaction as combination, decomposition, single-displacement, or double-displacement.
a. H2 + O2 → H2O
b. C + Fe2O3 → Fe + CO
c. H2SO4 + NaOH → H2O + Na2SO4
d. Al2(CO3)3 → Al2O3 + CO2
e. NH4I + Cl2 → NH4Cl + I2