Answer : The balanced chemical equation is,
[tex]2MnO_4^-(aq)+Mn(OH)_2(s)+4OH^-(aq)\rightarrow 3MnO_4^{2-}(aq)+2H_2O(l)[/tex]
The coefficient for [tex]OH^-[/tex] is, 4 and on reactant side of the equation [tex]OH^-(aq)[/tex] is present.
Explanation :
Rules for the balanced chemical equation in basic solution are :
The half reactions in the basic solution are :
Reduction : [tex]Mn(OH)_2(s)+1e^-\rightarrow MnO_4^{2-}(aq)[/tex] ......(1)
Oxidation : [tex]MnO_4^-(aq)+4OH^-(aq)\rightarrow MnO_4^{2-}(aq)+2H_2O(l)+2e^-[/tex].....(2)
Now multiply the equation (1) by 2 and then added both equation, we get the balanced redox reaction.
The balanced chemical equation in a basic solution will be,
[tex]2MnO_4^-(aq)+Mn(OH)_2(s)+4OH^-(aq)\rightarrow 3MnO_4^{2-}(aq)+2H_2O(l)[/tex]
Thus, the coefficient for [tex]OH^-[/tex] is, 4 and on reactant side of the equation [tex]OH^-(aq)[/tex] is present.