Statement I: In an octahedral complex, the five d orbitals of the met…

The correct answer is Option (3) → Statement I is correct but Statement II is false

In crystal field theory the ligands are treated as point charges; their repulsion on the metal d electrons removes the equal energy (degeneracy) of the five d orbitals.

Statement I: In an octahedral complex, the five d orbitals of the metal ion split into two sets, t_2g and e_g. — True. The \( d_{x^2-y^2} \) and \( d_{z^2} \) orbitals point at the six ligands and are raised in energy (the e_g set); \( d_{xy} \), \( d_{yz} \) and \( d_{xz} \) point between them and are lowered (the t_2g set).

Statement II: Weak field ligands such as Cl⁻ do not split the d orbitals of the metal ion. — False. Every ligand splits the d orbitals. A weak field ligand such as \( \ce{Cl^-} \) gives only a small splitting (Δ_o < P), which is why it forms high spin complexes.

NCERT (2026-27 edition):
5.5.4 Crystal Field Theory – “… Thus, the degeneracy of the d orbitals has been removed due to ligand electron-metal electron repulsions in the octahedral complex to yield three orbitals of lower energy, t_2g set and two orbitals of higher energy, e_g set.”

“… Some ligands are able to produce strong fields in which case, the splitting will be large whereas others produce weak fields and consequently result in small splitting of d orbitals. In general, ligands can be arranged in a series in the order of increasing field strength as given below: I^– < Br^– < SCN^– < Cl^– < S^2– < F^– < OH^– < C₂O₄^2– < H₂O < NCS^– < edta^4– < NH₃ < en < CN^– < CO

… Ligands for which Δ_o < P are known as weak field ligands and form high spin complexes.”