Question

Which of the following ions form most stable complex compound?

• A. Mn\(^{2+} \)
• B. Ni\(^{2+} \)
• C. Fe\(^{2+} \)
• D. Cu\(^{2+} \)

Hint:

Copper \( 2+ \) ions form the most stable complexes due to their higher charge density and smaller ionic size.

Answer 1

The Correct Option is D

Step 1: Identifying the stability of metal complexes.
Copper \( 2+ \) ions (Cu\(^{2+} \)) form the most stable complex compounds due to their smaller ionic size and higher charge density compared to the other ions listed.

Step 2: Explanation of the options.
- (1) Mn\(^{2+} \): Manganese \( 2+ \) ions do not form as stable complexes compared to copper \( 2+ \).
- (2) Ni\(^{2+} \): Nickel \( 2+ \) ions form stable complexes, but not as stable as copper \( 2+ \).
- (3) Fe\(^{2+} \): Iron \( 2+ \) ions are not as stable as copper \( 2+ \) ions in forming complexes.
- (4) Cu\(^{2+} \): Copper \( 2+ \) ions have a high charge density and form the most stable complexes.

Step 3: Conclusion.
The correct answer is (4) Cu\(^{2+} \).