Question

Which of the following pairs of ions will have same spin only magnetic moment values within the pair?
A. Zn²⁺, Ti²⁺
B. Cr²⁺, Fe²⁺
C. Ti³⁺, Cu²⁺
D. V²⁺, Cu⁺
Choose the correct answer from the options given below:

• A. C and D only
• B. A and D only
• C. A and B only
• D. B and C only

Answer 1

The Correct Option is D

Spin-only magnetic moment is calculated using the formula:

\[\mu = \sqrt{n(n+2)}\]

where n is the number of unpaired electrons and μ is the magnetic moment in Bohr magnetons.

We need to determine the number of unpaired electrons for each ion:

1. Zn²⁺ (d¹⁰), Ti²⁺ (d²): Zn²⁺ has 0 unpaired electrons, Ti²⁺ has 2.
2. Cr²⁺ (d⁴), Fe²⁺ (d⁶): Cr²⁺ has 4 unpaired electrons, Fe²⁺ has 4.
3. Ti³⁺ (d¹), Cu²⁺ (d⁹): Ti³⁺ has 1 unpaired electron, Cu²⁺ has 1.
4. V²⁺ (d³), Cu⁺ (d¹⁰): V²⁺ has 3 unpaired electrons, Cu⁺ has 0.

Therefore, the pairs with the same spin-only magnetic moment are B (Cr²⁺ and Fe²⁺) and C (Ti³⁺ and Cu²⁺).