Oxidation Reduction

a) Identify the substance oxidised, substance reduced, oxidising agent and reducing agent in the following reaction: 

b) In the reaction , what is oxidised and what is reduced? 

(i) Balance the following equations by oxidation number method:
(1) Cu + HNO3 → Cu (NO3)2 + NO2 + H2O)
(2) K2Cr2O7 + HCl → KCl + CrCl3 + H2O + Cl2
(ii) Give reasons for the following:
(1) HNO3 acts only as an oxidising agent while HNO2 can act both as a
reducing agent and an oxidising agent.
(2) Chlorine liberates iodine from KI solution.

How will you convert the following? (Give balanced equation.)
(1) Sodium acetate to methane

Find the oxidation number of:
(1) S in Na2S4 O6

2) S in