Final answer:
In a linear complex such as AgCl₂⁻, the (d) dz² orbital will have the highest energy due to direct alignment with the ligands causing increased electrostatic repulsion, as explained by crystal field theory.
Step-by-step explanation:
According to crystal field theory (CFT), in a linear complex, the d orbitals split into different energy levels due to electrostatic interactions with the ligands. For a linear complex such as AgCl₂⁻, the approximate arrangement of ligands aligns with the z-axis, causing a change in energy levels.
The energy of the dz² orbital will be the highest because it points directly along the line of the two ligands, resulting in greater electrostatic repulsion and higher energy relative to a spherical distribution of negative charge.
The other d orbitals (dxy, dxz, dyz, and dx²-y²) will have lower energies, with the dx²-y² orbital being affected by the repulsions less due to its orientation relative to the z-axis.
Consequently, the correct answer to which d orbital would be at the highest energy level in AgCl₂⁻ is dz².