Potassium permanganate acts as an oxidant in neutral,alkaline,as well as acidic media. The final products obtained from it in the three conditions are,respectively:

Identify the substance oxidised,reduced,oxidising agent,and reducing agent for each of the following reactions:
$(a)$ $2AgBr_{(s)} + C_6H_6O_{2(aq)} \to 2Ag_{(s)} + 2HBr_{(aq)} + C_6H_4O_{2(aq)}$
$(b)$ $HCHO_{(l)} + 2[Ag(NH_3)_2]^+_{(aq)} + 3OH^-_{(aq)} \to 2Ag_{(s)} + HCOO^-_{(aq)} + 2NH_{3(aq)} + 2H_2O_{(l)}$
$(c)$ $HCHO_{(l)} + 2Cu^{2+}_{(aq)} + 5OH^-_{(aq)} \to Cu_2O_{(s)} + HCOO^-_{(aq)} + 3H_2O_{(l)}$
$(d)$ $N_2H_{4(l)} + 2H_2O_{2(l)} \to N_{2(g)} + 4H_2O_{(l)}$
$(e)$ $Pb_{(s)} + PbO_{2(s)} + 2H_2SO_{4(aq)} \to 2PbSO_{4(s)} + 2H_2O_{(l)}$

Acidified potassium permanganate solution is decolourised by

Consider the reactions:
$2S_2O_3^{2-}{(aq)} + I_{2(s)} \to S_4O_6^{2-}{(aq)} + 2I^{-}{(aq)}$
$S_2O_3^{2-}{(aq)} + 2Br_{2(l)} + 5H_2O_{(l)} \to 2SO_4^{2-}{(aq)} + 4Br^{-}{(aq)} + 10H^{+}{(aq)}$
Why does the same reductant,thiosulphate,react differently with iodine and bromine?

$AgCl$ when heated with $Na_2CO_3$ gives:

In the reaction of phosphorus with concentrated $HNO_3$,the oxidized and reduced products respectively are