Question

An element has \(d^5\) configuration. The total number of electron exchanges possible for it is

• A. 18
• B. 10
• C. 12
• D. 15

Hint:

For a half-filled \(d^5\) configuration, all five electrons have parallel spins. The total number of exchange pairs is calculated by \(\frac{n(n-1)}{2}\).

Answer 1

The Correct Option is B

Step 1: Determine electron count for gold (Au, Z = 79).
After xenon core, fill 4f¹⁴, then 5d and 6s. Expected: 4f¹⁴ 5d⁹ 6s². But completely filled d¹⁰ is more stable, so one electron shifts from 6s to 5d.

Step 2: Write correct configuration.
[Xe] 4f¹⁴ 5d¹⁰ 6s¹.

Step 3: Final Answer:
[Xe] 4f¹⁴ 5d¹⁰ 6s¹.