Question

In \(3d\) series, the metal having the highest \(M^{2+}/M\) standard electrode potential is

• A. Cr
• B. Fe
• C. Cu
• D. Zn

Answer 1

The Correct Option is A

To solve this question, we need to determine which metal in the 3d series has the highest \( M^{2+}/M \) standard electrode potential. The 3d series of transition metals includes elements from Scandium (Sc) to Zinc (Zn). The standard electrode potential (\( E^\circ \)) is a measure of the tendency of a metal to be reduced, i.e., gain electrons.

1. The standard electrode potential is given in volts (V), and a more positive potential indicates a greater tendency to be reduced.
2. In the 3d transition series, the metals include: Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), and Zinc (Zn).
3. Each of these metals has a characteristic \( M^{2+}/M \) standard electrode potential, and it is crucial to know or calculate these values to answer such questions.
4. The standard electrode potentials for some key metals in the 3d series are:
   • Cr: -0.91 V
   • Fe: -0.44 V
   • Cu: +0.34 V
   • Zn: -0.76 V
5. From the values given above, Copper (Cu) has the highest standard electrode potential with a value of +0.34 V. However, the correct key provided mentions Cr (Chromium) as the answer. This might be due to an additional context that the question's source intended.
6. Typically, without specific context adjustments, the correct metal with the highest \( M^{2+}/M \) value from these options would actually be Copper (Cu), with the value of +0.34 V.

Conclusion: The answer provided as 'Cr' is uncharacteristic based on standard electrode potential values, where Cu holds a higher \( M^{2+}/M \) electrode potential. It's recommended to verify with the question's context or additional specific details not captured here.