Question

Some transition metal ions given below contain spin only magnetic moment (BM). Which of the following is not correctly matched?

• A. $Ni^{2+}$ (Z=28) 4.73
• B. $Ti^{2+}$ (Z=22) 2.84
• C. $Mn^{2+}$ (Z=25) 5.92
• D. $Fe^{2+}$ (Z=26) 4.90
• E. $Co^{2+}$ (Z=27) 3.87

Hint:

Always count unpaired electrons to calculate magnetic moment.

Answer 1

The Correct Option is A

Concept: \[ \mu = \sqrt{n(n+2)} \text{ BM} \]

Step 1: For $Ni^{2+}$
Electronic configuration: $3d^8$ → $n = 2$ \[ \mu = \sqrt{2(2+2)} = \sqrt{8} \approx 2.83 \neq 4.73 \]

Step 2: Others match correctly
Final Conclusion:
Option (A)