Question: which one of the following elements or ions is the strongest reducing agent?
Answer: For example, among Na, Cr, Cu+ and Cl−, Na is the strongest reducing agent and Cl− is the weakest one. Common reducing agents include metals potassium, calcium, barium, sodium and magnesium, and also compounds that contain the H− ion, those being NaH, LiH, LiAlH4 and CaH2.