What is the equivalent weight of $KMnO_4$ in acidic medium (in $g$)? (Molecular weight of $KMnO_4 = 158 \ g$)

$2 MnO_{4}^{-} + b C_{2}O_{4}^{2-} + c H^{+} \rightarrow x Mn^{2+} + y CO_{2} + z H_{2}O$
If the above equation is balanced with integer coefficients,the value of $c$ is ...........
(Round off to the Nearest Integer).

In the given chemical reaction,colors of the $Fe^{2+}$ and $Fe^{3+}$ ions,are respectively :
$5 Fe^{2+} + MnO_{4}^{-} + 8 H^{+} \rightarrow Mn^{2+} + 4 H_{2} O + 5 Fe^{3+}$

Balance the redox reaction where $Fe^{+2}$ in an acidic medium reduces $Cr_2O_7^{-2}$ ion to $Cr^{+3}$ ion,while $Fe^{+2}$ itself is oxidized to $Fe^{+3}$.

In alkaline medium,the reduction of permanganate anion involves a gain of $........$ electrons.

The dark purple colour of $KMnO_4$ disappears in the titration with oxalic acid in acidic medium. The overall change in the oxidation number of manganese in the reaction is.