Which one of the following items does NOT characterize a reducing agent? a. A reducing agent loses electrons. b. A reducing agent causes another species to be reduced. c. The oxidation number of a reducing agent increases. d. A good reducing agent is a metal in a high oxidation state, such as Mn7+.

A reducing agent is a species that reduces other compounds, and is thereby oxidized. The whole compound becomes the reducing agent. In other words, of a compound is oxidized, then they are the reducing agent. On the other hand, if the compound is reduced, it is an ozidizing agent.

Since we have established that a reducing agent is the compound being oxidized, we know that A is not our answer. An oxidized compound is losing electrons. Choice A states exactly this.

For B, this is true as we have established this already.

C is also correct. Since a reducing agent loses electrons, it becomes more positive. This makes the oxidation number increase.

D would be our correct answer. It is actually a good oxidizing agent is a metal in a high oxidation state, such as Mn⁷⁺.