Question

Which one of the following alkali metals is the weakest reducing agent as per their \( E^\circ \) values?

• A. \( K \)
• B. \( Cs \)
• C. \( Li \)
• D. \( Na \)

Hint:

A more negative standard reduction potential (\( E^\circ \)) means a stronger reducing agent. Among alkali metals, lithium is the strongest and sodium is the weakest reducing agent.

Answer 1

The Correct Option is D

Step 1: Understanding Reducing Power and \( E^\circ \) Values
- The standard reduction potential (\( E^\circ \)) of alkali metals determines their ability to lose electrons and act as reducing agents.
- A more negative \( E^\circ \) value indicates a stronger reducing agent.
- The standard reduction potentials (\( E^\circ \)) of alkali metals are: \[ Li = -3.04 V, \quad Na = -2.71 V, \quad K = -2.93 V, \quad Cs = -2.92 V \] Step 2: Identifying the Weakest Reducing Agent
- The reducing power of alkali metals increases down the group due to decreasing ionization energy.
- Lithium (\( Li \)) has the most negative \( E^\circ \) value, making it the strongest reducing agent.
- Sodium (\( Na \)) has the least negative \( E^\circ \) value among the given options, meaning it is the weakest reducing agent.
Conclusion: Sodium (Na) is the weakest reducing agent as per its \( E^\circ \) value.
Thus, the correct answer is Option (4): \( Na \).