The steric number H is calculated as H=21(V+M−C+A), where V is the number of valence electrons on the central atom, M is the number of monovalent atoms, C is the cationic charge, and A is the anionic charge.
For sp3d hybridization, H=5.
BrF5: H=21(7+5)=6 (sp3d2)
XeF5−: H=21(8+5+1)=7 (sp3d3)
BF4−: H=21(3+4+1)=4 (sp3)
ICl4−: H=21(7+4+1)=6 (sp3d2)
XeF4: H=21(8+4)=6 (sp3d2)
SF4: H=21(6+4)=5 (sp3d)
NH4+: H=21(5+4−1)=4 (sp3)
ClF3: H=21(7+3)=5 (sp3d)
XeF2: H=21(8+2)=5 (sp3d)
ICl2−: H=21(7+2+1)=5 (sp3d)
The species with sp3d hybridization are SF4, ClF3, XeF2, and ICl2−.
The number of such species is 4.
Answer: 4