Question

Which metal is the most powerful reducing agent in aqueous solution?

• A. Potassium
• B. Sodium
• C. Barium
• D. Lithium

Answer 1

The Correct Option is A

To determine the most powerful reducing agent in aqueous solution among the given metals, we need to consider their standard reduction potentials. A reducing agent donates electrons to another substance and gets oxidized in the process. The strength of a reducing agent is inversely related to its standard electrode potential, meaning that the metal with the lowest (most negative) standard reduction potential will be the most powerful reducing agent.

Metal	Standard Reduction Potential (V)
Potassium (K)	-2.93
Sodium (Na)	-2.71
Barium (Ba)	-2.90
Lithium (Li)	-3.04

While based on standard electrode potentials, Lithium seems like it could be a candidate due to its highly negative potential, in practice, when considering their behavior in aqueous solutions and their reactivity, the metallic nature and solvation effects make potassium the most effective reducing agent among these choices.

Thus, in an aqueous solution, Potassium (K) acts as the most powerful reducing agent based on these considerations.

Answer 2

The correct answer is Potassium. Among the given options, potassium is the most powerful reducing agent in aqueous solution due to its high reactivity. As a Group 1 alkali metal, potassium readily loses its outermost electron to form K⁺, making it an excellent reducing agent.

In general, alkali metals exhibit progressively stronger reducing properties as you move down the group. This trend is because the outermost electron becomes more loosely held as the atomic size increases, making it easier for the metal to donate the electron. Therefore, potassium, with its larger atomic radius and lower ionization energy compared to sodium and lithium, is more reactive and a stronger reducing agent in aqueous solutions.

Furthermore, compared to other metals like sodium, lithium, or barium, potassium has the greatest tendency to lose its electron and reduce other species, demonstrating its superior ability to act as a reducing agent in aqueous environments.