Answer : The correct option is, (1) \(K^++e^-\rightarrow K\)
Explanation :
Oxidation-reduction reaction : It is a type of reaction where the oxidation and reduction reaction takes place simultaneously.
Oxidation reaction : It is a 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 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.
As per question, the half-reaction equation of reduction of a potassium ion will be :
\(K^++e^-\rightarrow K\)
In this reaction, the oxidation state of potassium changes from (+1) to (0) that means the oxidation state decreases. So, this reaction shows the half-reaction equation of reduction of a potassium ion.
Therefore, the correct option is, (1) \(K^++e^-\rightarrow K\)
