Question

Which of the following elements has positive standard reduction potential?

• A. Al
• B. Sn
• C. Cu
• D. Zn

Hint:

Metals below hydrogen in the electrochemical series have positive reduction potentials.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept
A positive standard reduction potential means the ion is reduced more easily than \(\text{H}^{+}\).

Step 2: Compare values
\(E^{\circ}(\text{Al}^{3+}/\text{Al})=-1.66\) V.
\(E^{\circ}(\text{Sn}^{2+}/\text{Sn})=-0.14\) V.
\(E^{\circ}(\text{Zn}^{2+}/\text{Zn})=-0.76\) V.
\(E^{\circ}(\text{Cu}^{2+}/\text{Cu})=+0.34\) V.

Step 3: Conclusion
Copper lies below hydrogen in the electrochemical series, so it has a positive value.

Final Answer:
Copper has a positive standard reduction potential. \[ \boxed{\text{(C) }\text{Cu}} \]