Given two half reactions as follows: a2+ → 2 a2+ + 3 e− 4 e− + b → b4− what would you multiply each half-reaction by, to cancel out the electrons?

In order to cancel the electrons,. the oxidation half reaction must be multiplied by 4 and the reduction half reaction must be multiplied by 3.

Explanation:

Oxidation reaction is defined as the chemical reaction in which an atom looses its electrons. The oxidation number of the atom gets increased during this reaction.

Reduction reaction is defined as the chemical reaction in which an atom gains electrons. The oxidation number of the atom gets reduced during this reaction.

The half cell reactions for the above reaction follows:

Oxidation half reaction:  

Reduction half reaction:  

Thus, in order to cancel the electrons,. the oxidation half reaction must be multiplied by 4 and the reduction half reaction must be multiplied by 3.

Thus,

4*Oxidation half reaction:  

3*Reduction half reaction:  

Overall reaction:-

it's all four options.