The hybridization of copper in [CuCl₄]2− is:
[CuCl₄]2− (Cu₂+, d9) is tetrahedral with 4 Cl− ligands, using sp3 hybridization (outer orbitals).
Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Bonding - Valence Bond Theory and Hybridisation