Balance each of the following equations according to the half- reaction method:
(a) mno4- + no2- --> mno2 + no3- (in base)
(b) mno42- --> mno4- +mno2 (in base)
(c) br2 + so2 --> br- + so42- (in acid)

Explanation :

Redox reaction or Oxidation-reduction reaction : It is defined as the reaction in which the oxidation and reduction reaction takes place simultaneously.

Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.

Reduction reaction : It is defined as the reaction in which a substance gains electrons. In this, oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.

(a) The given chemical reaction is :

The oxidation-reduction half reaction will be :

Oxidation :

Reduction :

In order to balance the electrons, we multiply the oxidation reaction by 3 and reduction reaction by 2 then added both equation, we get the balanced redox reaction.

The balanced chemical equation in a basic solution will be,

(b) The given chemical reaction is :

The oxidation-reduction half reaction will be :

Oxidation :

Reduction :

In order to balance the electrons, we multiply the oxidation reaction by 2 and then added both equation, we get the balanced redox reaction.

The balanced chemical equation in a basic solution will be,

(c) The given chemical reaction is :

The oxidation-reduction half reaction will be :

Oxidation :

Reduction :

The electrons in oxidation and reduction reaction are same. Now add both the equation, we get the balanced redox reaction.

The balanced chemical equation in a acidic solution will be,

i think it's letter a.