${\mathrm{Cu}}_2\mathrm{S}+{\mathrm{MnO}}_4^{-}\rightleftharpoons {\mathrm{Cu}}^{2+}+{\mathrm{SO}}_2+{\mathrm{Mn}}^{2+}$

How many electrons will be lost from $1$ mole of ${\mathrm{Cu}}_2\mathrm{S}$ in the above reaction?

${\mathrm{C}}_2{{\mathrm{O}}_4}^{2-}+{{\mathrm{MnO}}_4}^{-}\to {\mathrm{Mn}}^{2+}+{\mathrm{CO}}_2$

The above reaction takes place in

Which among the following are the cases of disproportionation reaction?

a. ${\mathrm{Cl}}_2+2{\mathrm{OH}}^{-}\to {\mathrm{Cl}}^{-}+{\mathrm{H}}_2\mathrm{O}+{\mathrm{ClO}}_3^{-}$

b. $2\mathrm{HgO}\to 2\mathrm{Hg}+{\mathrm{O}}_2$

c. $2{\mathrm{HCuCl}}_2\to \mathrm{Cu}+{\mathrm{Cu}}^{2+}+4{\mathrm{Cl}}^{-}+2{\mathrm{H}}^{+}$

d. ${\mathrm{MgCO}}_3\to \mathrm{MgO}+{\mathrm{CO}}_2$

$\mathrm{S}+12{\mathrm{OH}}^{-}\to 4{\mathrm{S}}^{2-}+2{\mathrm{S}}_2{\mathrm{O}}_3^{2-}+6{\mathrm{H}}_2\mathrm{O}$

The molecular state of sulphur as a reactant in the above reaction is

${\mathrm{H}}_2\mathrm{S}+{\mathrm{H}}_2{\mathrm{O}}_2\to \mathrm{S}+2{\mathrm{H}}_2\mathrm{O}$

The behaviour of ${\mathrm{H}}_2{\mathrm{O}}_2$ depicted as in the above reaction is