Choose all of the statements from below which are true about oxidation and reduction. Oxidation and reduction are opposite processes with respect to bookkeeping electrons. Oxidation is what happens when an element in a substance gains electrons. Electrons appear on the right side of an oxidation half reaction. An oxidant is an oxidizing agent, which becomes reduced during the course of a redox reaction. Reduction is what happens when an element in a substance loses electrons. Electrons appear on the right side of a reduction half reaction. A reductant is an reducing agent, which becomes oxidized during the course of a redox reaction.