Oxidation of thiosulphate $S_2O_3^{2-}$ ion by iodine gives

$PbS + 4O_3 \,\to ?\,+\,4O_2$

If the molecular weights of $Na_2S_2O_3$ and $I_2$ are $M_1$ and $M_2$ respectively, then what will be the equivalent weights of $Na_2S_2O_3$ and $I_2$ in the following reaction?
$2S_2O_3^{2-} + I_2 \longrightarrow S_4O_6^{2-} + 2I^-$

$aIO_3^- + bI^- + 6H^+ \to cI_2 + 3H_2O$
In the above reaction,the coefficients $a$,$b$,and $c$ are respectively:

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:

Find the equivalent weight of $MnO_4^{-}$ for acid medium reactions. (Atomic weight of $Mn = 55$,Atomic weight of $O = 16$)