To precipitate as ${\mathrm{Ag}}_2\mathrm{S}\left(\mathrm{s}\right)$, all Ag+ present in 250 mL of a saturated solution of ${\mathrm{AgBrO}}_3$ requires $3.405 {\mathrm{cm}}^3$ of ${\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)$ measured at STP (Assuming ${\mathrm{H}}_2\mathrm{S}$ is enough soluble in water). ${\mathrm{K}}_{\mathrm{sp}}$ of ${\mathrm{AgBrO}}_3$ is:

$\left[{\mathrm{K}}_{\mathrm{sp}}\left({\mathrm{Ag}}_2 \mathrm{S}\right)={10}^{-50},{\mathrm{K}}_{\mathrm{a}}\left({\mathrm{H}}_2 \mathrm{S}\right)={10}^{-21}\right]$