Balance the reactions in the following.
a) C₂H₃Cl + O₂ → CO₂ + H₂O + HCl
b) C₇H₆O₂ + O₂ → CO₂ + H₂O
c) SnO₂ + H₂ → H₂O + Sn
d) H₂ + N₂ → NH₃