1.) Use the changes in oxidation number to identify which atoms are oxidized and which are reduced in each reaction. a.) 2Na(s) + Cl2(g) --> 2NaCl(s)

Na --> Na+1 is oxidized Cl2 --> Cl- is reduced

b.) 2HNO3(aq) + 6HI(aq) --> 2NO(g) + 3I2(s) + 4H2O(l)

N+5 --> N+2 is reduced I-1 --> I2 is oxidized

c.) 3H2S(g) + 2HNO3(aq) --> 3S(s) + 2NO(g) + 4H2O(l)

d.) 2PbSO4(s) + 2H2O(l) --> Pb(s) + PbO2(s) + H2SO4(aq)