Question

The standard reduction potentials at 298 K for half-cell reactions are given:
\( \mathrm{Zn}^{2+} + 2e^{-} \rightarrow \mathrm{Zn};\ -0.762\,\text{V} \)
\( \mathrm{Cr}^{3+} + 3e^{-} \rightarrow \mathrm{Cr};\ -0.74\,\text{V} \)
\( 2\mathrm{H}^{+} + 2e^{-} \rightarrow \mathrm{H}_{2};\ 0.00\,\text{V} \)
\( \mathrm{Fe}^{3+} + e^{-} \rightleftharpoons \mathrm{Fe}^{2+};\ +0.77\,\text{V} \)
The strongest reducing agent is:

• A. $Zn(s)$
• B. $Cr(s)$
• C. $H_{2}(g)$
• D. $Fe^{2+}(aq)$

Hint:

More negative $E^{\circ}$ = Stronger Reducing Agent.

Answer 1

The Correct Option is A

Step 1: Concept
Reducing agent strength is directly related to the negative value of standard reduction potential.
Step 2: Analysis
A higher negative potential indicates a greater tendency to lose electrons (undergo oxidation).
Step 3: Conclusion
Among the given values, Zinc has the highest negative potential ($-0.762V$), making it the strongest reducing agent.
Final Answer: (A)