JEE Main · 2024 · 31 Jan 2024 · Shift 1 · Chemical Bonding and Molecular Structure

Hybridisation of the central atom in each species:
$\mathrm{N}{\mathrm{H}}_3$: $s{p}^3$ (3 bond pairs + 1 lone pair)
$\mathrm{S}{\mathrm{O}}_2$: $s{p}^2$ (bent, one lone pair in a trigonal-planar arrangement)
$\mathrm{Si}{\mathrm{O}}_2$: $s{p}^3$ (each Si is tetrahedrally bonded to 4 O in the extended lattice)
$\mathrm{BeC}{\mathrm{l}}_2$: $sp$ (linear)
$\mathrm{C}{\mathrm{O}}_2$: $sp$ (linear)
${\mathrm{H}}_2\mathrm{O}$: $s{p}^3$ (bent, two lone pairs)
$\mathrm{C}{\mathrm{H}}_4$: $s{p}^3$ (tetrahedral)
$\mathrm{B}{\mathrm{F}}_3$: $s{p}^2$ (trigonal planar)

Species with $s{p}^3$ central atom: $\mathrm{N}{\mathrm{H}}_3,\mathrm{Si}{\mathrm{O}}_2,{\mathrm{H}}_2\mathrm{O},\mathrm{C}{\mathrm{H}}_4$ -- a total of 4.