Identify the substance oxidised, reduced , oxidising agent and reducing agent for each of the following reactions :
(a) `2AgBr(s)+C_6H_6O_2(aq) rarr2Ag(s)+2HBr(aq)+C_6H_4O_2(aq)`
(b) `HCHO(l) +2[Ag(NH_3)_2]^(2+)(aq) +3OH^(-) (aq) rarr 2Ag(s) + HCOO^(-)(aq) +4NH_3(aq) +2H_2O(l)`
(c) `HCHO(l)+2Cu^(2+)(aq)+5OH^(-)(aq) rarrCu_2O(s)+HCOO^(-) (aq)+3H_2O(l)`
(d) `N_2H_4(l)+2H_2O_2(l)rarrN_2(g) +4H_2O(l)`
(e) `Pb(s) + PbO_2(s) +2H_2SO_4(aq)rarr2PbSO_4(s)+2H_2O(l)`

Explanation

`PbO_2` : reduced `" "Pb(s)` , oxidised
`PbO_2(s)` : oxidising agent , `Pb(s)` : reducing agent