Question

The magnetic moment of a transition metal complex is found to be \(4.90\) BM. The number of unpaired electrons present is:

• A. 2
• B. 3
• C. 4
• D. 5

Hint:

Important values: \[ 1.73 \rightarrow 1 \] \[ 2.83 \rightarrow 2 \] \[ 3.87 \rightarrow 3 \] \[ 4.90 \rightarrow 4 \] \[ 5.92 \rightarrow 5 \] These values are frequently asked in CUET.

Answer 1

The Correct Option is C

Concept: Magnetic moment is calculated using the spin-only formula: \[ \mu=\sqrt{n(n+2)} \] where:
• \(\mu\) = magnetic moment in BM
• \(n\) = number of unpaired electrons

Step 1: Substitute the given value.
\[ 4.90=\sqrt{n(n+2)} \] Squaring both sides: \[ 24.01=n(n+2) \]

Step 2: Find suitable value of \(n\).
For \(n=4\): \[ 4(4+2) = 24 \] \[ \sqrt{24} = 4.90 \] The value matches perfectly.

Step 3: Conclusion.
Number of unpaired electrons: \[ \boxed{4} \]