In the reaction of oxalate with permanganate in acidic medium,the number of electrons involved in producing one molecule 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.

$Na_2S_2O_3 + I_2 \to$ Product is

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$PbO_2 + 4HNO_3 (Conc.) \longrightarrow Pb(NO_3)_2 + 2H_2O + O_2$

In a balanced equation $H_2SO_4 + x \ HI \to H_2S + y \ I_2 + z \ H_2O$,the values of $x, y, z$ are

$KMnO_4$ oxidises oxalic acid in acidic medium. The number of $CO_2$ molecules produced per mole of $KMnO_4$ is