Final answer:
The strongest reducing agent among sodium (Na), chlorine (Cl), hydrogen (H), and zinc (Zn) is sodium (Na). Sodium is a very reactive metal that readily loses an electron, thus acts powerfully as a reducing agent by providing electrons to other substances.
Step-by-step explanation:
The task is to choose the strongest reducing agent from the given list: sodium (Na), chlorine (Cl), hydrogen (H), and zinc (Zn). A reducing agent (or reductant) is something that donates electrons to another species in a chemical reaction, thus itself being oxidized in the process.
Sodium (Na) is a very reactive metal that easily loses an electron to form Na+. When Sodium reacts with chlorine (Cl), a pale yellow-green gas, sodium is oxidized while chlorine is reduced, resulting in the formation of sodium chloride (table salt). Thus, in this context, sodium tends to be a reducing agent that provides electrons to other substances.
Zinc (Zn) is also a metal known to act as a reducing agent, but it is less reactive than sodium. Hydrogen (H) can be a reducing agent but is not as strong as the alkali metals. Chlorine, being a halogen, typically serves as an oxidizing agent rather than a reducing agent. Therefore, of the options provided, sodium (Na) is the strongest reducing agent as it most readily donates electrons.