• # question_answer Which d-orbital is involved in $s{{p}^{3}}d$ hybridisation and why?

${{d}_{{{z}^{2}}}}$. The three planar triangular hybrid orbitals may be assumed to be formed from one s and two p-orbitals (sp2) and the remaining p-orbital may combine with ${{d}_{{{z}^{2}}}}$ to form two axial hybrid orbitals.