WAEC Chemistry 2025 Paper

Concept:Orbitals that possess identical energy are known as degenerate orbitals.Explanation:In an isolated transition metal atom or ion, there is no surrounding ligand field or external electric field to disturb the electrons.As a result, all five $d$-orbitals, namely $d_{xy}$, $d_{yz}$, $d_{zx}$, $d_{x^2-y^2}$, and $d_{z^2}$, have exactly the same energy level.When no ligand approaches the metal, the spherical symmetry of the free atom or ion is maintained.Therefore, the five $d$-orbitals remain unsplit and equivalent in energy.This condition changes only when ligands create a crystal field, which splits the $d$-orbitals into different energy sets.Since equal energy is the defining feature of degenerate orbitals, these five $d$-orbitals are correctly called degenerate.Answer:A. degenerate