The following reaction was carried out in ${\mathrm{H}}_2\mathrm{O}$

   ${\mathrm{Cl}}_2+2{\mathrm{I}}^{-}\to {\mathrm{I}}_2+2{\mathrm{Cl}}^{-}$

The initial concentration of ${\mathrm{I}}^{-}$ was $0.25 \mathrm{mol} {\mathrm{L}}^{-}$ and concentration after $10$ min. is $0.23\mathrm{mol} {\mathrm{L}}^{-}$.Calculate rate of disappearance of ${\mathrm{I}}^{-}$ and appearance of ${\mathrm{I}}_2.$