Write the balanced equation for the oxidation of sulphite ions to sulphate ions in acid medium by permanganate ion.

Phosphorus when heated with $\mathrm{NaOH}$ solution gives phosphine (${\mathrm{PH}}_3$) and ${\mathrm{H}}_2{\mathrm{PO}}_2^{-}$. 

Give the balanced equation.

Balance the following equation:

$\mathrm{Cr}{\left(\mathrm{OH}\right)}_3 + {\mathrm{IO}}_3^{-} \stackrel{{\mathrm{OH}}^{-}}{\to }{\mathrm{I}}^{-} + {\mathrm{CrO}}_4^{-2}$.

Balance the following equation by the oxidation number method.

${\mathrm{MnO}}_4^{2-}+ {\mathrm{Cl}}_2 \to {\mathrm{MnO}}_4^{-} + {\mathrm{Cl}}^{-}$.

How are the end point of titration detected in the following reaction.

${\mathrm{MnO}}_4^{-2}$ oxidises ${\mathrm{Fe}}^{2+}$.

How are the end point of titration detected in the following reaction.

${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$ oxidises ${\mathrm{Fe}}^{2+}$.