Concept:Oxidation is the loss of electrons by a substance during a chemical reaction.
Explanation:When a substance is oxidized, it loses electrons.
Modern chemistry defines oxidation as the process in which an atom, molecule, or ion loses one or more electrons.
This loss of electrons causes the oxidation state of the substance to increase.
For example, when sodium forms
Na+, the reaction
Na→Na++e− shows that sodium is oxidized because it loses an electron.
The electrons lost by the oxidized substance are gained by another substance, which is reduced.
Thus, oxidation and reduction always occur together in a redox reaction.
The older definition of oxidation involved gaining oxygen atoms, but the modern and more general definition is based on electron transfer.
Gaining electrons describes reduction, not oxidation.
Losing protons describes acid–base behavior, not oxidation.
Answer:A. Loses electrons