Final answer:
The molecular geometry of SF₅⁻ is square pyramidal and the sulfur undergoes sp³d² hybridization to accommodate five bonding pairs and one lone pair of electrons.
Step-by-step explanation:
The molecular geometry of the molecular anion SF5⁻ is square pyramidal. When looking at its hybridization, we have to consider the hybridization of the sulfur (S) atom's orbitals. In SF5⁻, sulfur has five bonding pairs with fluorine atoms and one lone pair of electrons, which means there are six regions of electron density in total.
Hence, the sulfur atom undergoes sp³d² hybridization due to the combination of one 3s orbital, three 3p orbitals, and two 3d orbitals forming six hybrid orbitals. These orbitals are then directed towards the corners of an octahedron, with one of the positions being occupied by the lone pair. This results in the square pyramidal structure due to the lone pair's position influencing the geometry of the molecule.