How many of the following compounds will decolourize the colour of acidified ${\mathrm{KMnO}}_4$?

${\mathrm{H}}_2\mathrm{S}$        ${\mathrm{FeSO}}_4$  ${\mathrm{NaNO}}_2$

${\mathrm{Na}}_2{\mathrm{SO}}_3$   $\mathrm{PbS}$      ${\mathrm{Na}}_2\mathrm{S}$

${\mathrm{NaNO}}_3$    ${\mathrm{Na}}_2{\mathrm{SO}}_4$  ${\mathrm{CO}}_2$

${\mathrm{SO}}_3$         ${\mathrm{P}}_2{\mathrm{O}}_5$

$\mathrm{S}$ and ${\mathrm{Mn}}^{2+}$ are produced when${\mathrm{H}}_2\mathrm{S}$ gas is passed through an acidified ${\mathrm{KMnO}}_4$  solution. It neutralises the acidified ${\mathrm{KMnO}}_4$ hue.
Because ${\mathrm{KMnO}}_4$  is an oxidising agent, its colour is changed when it combines with acidified${\mathrm{FeSO}}_4$ and oxidises.

The compounds which will decolourize the colour of acidified ${\mathrm{KMnO}}_4$ are,

${\mathrm{H}}_2\mathrm{S},{\mathrm{FeSO}}_4,{\mathrm{NaNO}}_2,{\mathrm{Na}}_2{\mathrm{SO}}_3,\mathrm{PbS},{\mathrm{Na}}_2\mathrm{S}$