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?

What is the oxidation state of $\mathrm{Cr}$ in ${\left[\mathrm{Cr}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Cl}}_2\right]}^{+}$ ?

Which of the following chemical reactions depicts the oxidizing behaviour of ${\mathrm{H}}_2{\mathrm{SO}}_4$?