JEE Main · 2026 · 05 Apr 2026 · Shift 1 · Chemical Bonding and Molecular Structure

A central atom is $s{p}^{3}d$ hybridised when five electron pairs, bonding plus lone, surround it. Counting these: $\mathrm{S}{\mathrm{F}}_4$ has four bonds and one lone pair, $\mathrm{Cl}{\mathrm{F}}_3$ three bonds and two lone pairs, $\mathrm{Xe}{\mathrm{F}}_2$ two bonds and three lone pairs, and $\mathrm{IC}{\mathrm{l}}_2^{-}$ two bonds and three lone pairs, each giving five pairs and $s{p}^{3}d$ geometry. The others have four pairs ($\mathrm{B}{\mathrm{F}}_4^{-}$, $\mathrm{N}{\mathrm{H}}_4^{+}$), six pairs ($\mathrm{Br}{\mathrm{F}}_5$, $\mathrm{IC}{\mathrm{l}}_4^{-}$, $\mathrm{Xe}{\mathrm{F}}_4$) or seven pairs ($\mathrm{Xe}{\mathrm{F}}_5^{-}$). The number of species with an $s{p}^{3}d$ central atom is $4$.