Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: All redox reactions occur with a simultaneous change in the oxidation numbers of some atoms. At least two elements must change their oxidation numbers. When an oxidation number of an atom is increased in the course of a redox reaction, that atom is being oxidized. When an oxidation number of an atom is decreased in the course of a redox reaction, that atom is being reduced. Thus oxidation and reduction can also be defined in terms of increasing or decreasing oxidation numbers, respectively. Saylor URL: http://www. saylor. org/books. Answer: reduced
Output:
When an oxidation number of an atom is decreased in the course of a redox reaction, that atom is being what?