Which is the weakest reducing agent among Li+, Li, F-, F2?

• A. Li+
• B. Li
• C. F-
• D. F2

Answer: (C)

Reducing agents donate electrons, so their strength is tied to how readily they can be oxidized. Lithium metal is easy to oxidize, so it is a strong reducing agent. A molecule like F2 tends to gain electrons to become fluoride, making it a powerful oxidizing agent rather than a reducer. The lithium ion is already in a high oxidation state and isn’t prone to donating electrons; it won’t act as a reducing agent in ordinary conditions. The fluoride ion, however, is already in a very reduced form for fluorine chemistry and would have to lose an electron to become neutral fluorine or to form F2, which is energetically unfavorable. That makes it the least willing to donate electrons among the options, hence the weakest reducing agent.