Answer: The inner (n-1)d subshell (e.g., 3d with 4s, 4p for period 4 metals).
- A The inner (n-1)d subshell (e.g., 3d with 4s, 4p for period 4 metals)
- B The outer nd subshell instead of the inner (n-1)d subshell under most conditions encountered
- C 4f orbitals borrowed from the lanthanide series as frequently observed in practice
- D 5d orbitals regardless of which period the metal belongs to in many documented cases
Correct answer: A. The inner (n-1)d subshell (e.g., 3d with 4s, 4p for period 4 metals)
Explanation: Inner orbital (low spin) complexes: metal uses (n-1)d, ns, and np orbitals for hybridisation (e.g., d<sup>2</sup>sp<sup>3</sup> for octahedral).
The three common coordination geometries: octahedral (6 ligands), tetrahedral (4 ligands), and square planar (4 ligands in one plane).
Concept context
Study of compounds where a central metal atom is bonded to surrounding ligands. Covers nomenclature, types of isomerism, bonding theories (VBT, CFT), and applications in medicine, photography, and industry.