Which of the following samples of reducing agents is /are chemically equivalent to $25 \mathrm{mL}$ of $0.2 \mathrm{N}$ ${\mathrm{KMnO}}_4$ to be reduced to ${\mathrm{Mn}}^{2+}$ and water:

If mass of ${\mathrm{KHC}}_2{\mathrm{O}}_4$ ( potassium acid oxalate) is required to reduce $100 \mathrm{mL}$ of $0.02 \mathrm{M} {\mathrm{KMnO}}_4$ in acidic medium is $\mathrm{x} \mathrm{g}$ and to neutralise $100 \mathrm{mL}$ $0.05 \mathrm{M} \mathrm{Ca}(\mathrm{OH}{)}_2$ is $\mathrm{y} \mathrm{g},$ then which of the following options may be correct?

The number of acids having central atom in $+3$ oxidation state among the following:
$\left(\mathrm{a}\right)$ ${\mathrm{HNO}}_2$
$\left(\mathrm{b}\right)$ ${\mathrm{HNO}}_3$
$\left(\mathrm{c}\right)$ ${\mathrm{H}}_3{\mathrm{PO}}_2$
$\left(\mathrm{d}\right)$ ${\mathrm{H}}_3{\mathrm{PO}}_3$
$\left(\mathrm{e}\right)$ ${\mathrm{H}}_3{\mathrm{PO}}_4$
$\left(\mathrm{f}\right)$ ${\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_5$
$\left(\mathrm{g}\right)$ ${\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_7$
$\left(\mathrm{h}\right)$ ${\mathrm{H}}_2{\mathrm{SO}}_3$
$\left(\mathrm{i}\right)$ ${\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_7$
$\left(\mathrm{j}\right)$ ${\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_8$
$\left(\mathrm{k}\right)$ ${\mathrm{H}}_2{\mathrm{SO}}_4$

For the given reaction:-

 ${\mathrm{I}}^{-}+\mathrm{C}!{\mathrm{O}}_3^{-}+{\mathrm{H}}_2{\mathrm{SO}}_4⟶{\mathrm{Cl}}^{-}+{\mathrm{HSO}}_4^{-}+{\mathrm{I}}_2$
What are the correct statement(s) in the balanced equation?