Balance the following reaction by the ion-electron method:

${{\mathrm{MnO}}_4}^{-}\left(\mathrm{aq}\right)+{\mathrm{SO}}_2\left(\mathrm{g}\right) \to {\mathrm{Mn}}^{2+}\left(\mathrm{aq}\right)+{{\mathrm{HSO}}_4}^{-}\left(\mathrm{aq}\right)$ (in acidic solution).

Balance the following redox reactions by ion $-$ electron method :

(c) ${\mathrm{H}}_2{\mathrm{O}}_{2 \left(\mathrm{aq}\right)} + {\mathrm{Fe}}^{2+}{ }_{\left(\mathrm{aq}\right)} \to {\mathrm{Fe}}^{3+}{ }_{\left(\mathrm{aq}\right)} + {\mathrm{H}}_2\mathrm{O}{ }_{\left(\mathrm{l}\right)}$ (in acidic solution)

Balance the following redox reaction by the ion-electron method:

${\mathrm{Cr}}_2{{\mathrm{O}}_7}^{2-}\left(\mathrm{aq}\right)+{\mathrm{SO}}_2\left(\mathrm{g}\right) \to {\mathrm{Cr}}^{3+}\left(\mathrm{aq}\right)+{{\mathrm{SO}}_4}^{2-}\left(\mathrm{aq}\right)$ (in acidic solution).

What sorts of informations can you draw from the following reaction ?

$(\mathrm{CN}{)}_{2\left(\mathrm{g}\right) }+ 2{{\mathrm{OH}}^{-}}_{\left(\mathrm{aq}\right)}\to {{\mathrm{CN}}^{-}}_{\left(\mathrm{aq}\right)} + {{\mathrm{CNO}}^{-}}_{\left(\mathrm{aq}\right)} +{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{I}\right)}$

Consider the elements :
$\mathrm{C}\mathrm{s}, \mathrm{N}\mathrm{e}, \mathrm{I}$ and $\mathrm{F}$

Identify the element that exhibits only negative oxidation state, identify the element that exhibits only positive oxidation state, identify the element that exhibits both positive and negative oxidation states and identify the element which exhibits neither the negative nor does the positive oxidation state.