Which of the following is a redox reaction?

The reaction,$3 ClO^{-} \rightarrow ClO_3^{-} + 2 Cl^{-}$ occurs in two steps:
$i.$ $2 ClO^{-} \rightarrow ClO_2^{-} + Cl^{-}$
$ii.$ $ClO_2^{-} + ClO^{-} \rightarrow ClO_3^{-} + Cl^{-}$
The reaction intermediate is:

$KMnO_4$ acts as an oxidising agent in alkaline medium. When alkaline $KMnO_4$ is treated with $KI$,iodide ion is oxidized to

After balancing the equation,$C_2O_4^{2-} + H^+ + MnO_4^- \longrightarrow CO_2 + Mn^{2+} + H_2O$,the coefficient of $CO_2$ is:

Consider the reactions:
$(a)$ $6CO_{2(g)} + 6H_2O_{(l)} \to C_6H_{12}O_{6(aq)} + 6O_{2(g)}$
$(b)$ $O_{3(g)} + H_2O_{2(l)} \to H_2O_{(l)} + 2O_{2(g)}$
Why is it more appropriate to write these reactions as:
$(a)$ $6CO_{2(g)} + 12H_2O_{(l)} \to C_6H_{12}O_{6(aq)} + 6H_2O_{(l)} + 6O_{2(g)}$
$(b)$ $O_{3(g)} + H_2O_{2(l)} \to H_2O_{(l)} + O_{2(g)} + O_{2(g)}$
Also,suggest a technique to investigate the reaction mechanism (path) of the above $(a)$ and $(b)$ redox reactions.

Acidified potassium dichromate on reacting with a sulphite is reduced to