Oxidation is best defined as
- A. loss of electrons and an increase in oxidation number
- B. gain of electrons and a decrease in oxidation number
- C. gain of hydrogen only
- D. loss of oxygen only
Explanation
The modern definition is in terms of electrons, so oxidation is loss and reduction is gain, remembered as OIL RIG. Definitions based on adding oxygen or removing hydrogen are older special cases that fail for reactions in which neither element is present. Every oxidation must be accompanied by a reduction, since the electrons lost by one species are gained by another.