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

Answer: (D)

B and C only

Answer 2

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. Zn 2+ (d10), Ti2+ (d2): Zn2+ has 0 unpaired electrons, Ti2+ has 2.
2. Cr 2+ (d4), Fe2+ (d6): Cr2+ has 4 unpaired electrons, Fe2+ has 4.
3. Ti 3+ (d1), Cu2+ (d9): Ti3+ has 1 unpaired electron, Cu2+ has 1.
4. V 2+ (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+).