Identify the atoms that are oxidized and reduced, the change in oxidation state for each, and the oxidizing and reducing agents in each of the following equations:
a) Mg(s) + NiCl2(aq) ? MgCl2(aq) + Ni(s)
b) PCl3(l) + Cl2(g) ? PCl5(s)
c) C2 H4(g) + 3O2(g) ? 2CO2(g) + 2H2 O(g)
d) Zn(s) + H2 SO4(aq) ? ZnSO4(aq) + H2(g)
e) 2K2 S2 O3(s) + I2(s) ? K2 S4 O6(s) + 2KI(s)
f) 3Cu(s) + 8HNO3(aq) ? 3Cu(NO3)2(aq) + 2NO(g) + 4H2 O(l)