In which of the following molecules the central atom does not have sp3 hybridization?
Explanation
For neutral molecules
No. of electron pairs = No. of atoms bonded to it + 1/2[Gp. no. of central atom - Valency of central atom]
$$ \therefore $$For CH4, no. of e- pairs = 4 + 1/2[4 - 4] = 4 (sp3 hybridisation)
For SF4, no. of e- pairs = 4 + 1/2[6 - 4] = 5 (sp3d hybridisation)
and For ions,
No. of electron pairs = No. of atoms bonded to it + 1/2[Gp. no. of central atom - Valency of central atom $$ \pm $$ No. of electrons]
$$ \therefore $$For BF4-, no. of e- pairs = 4 + 1/2[3 - 4 + 1] = 4 (sp3 hybridisation)
For NH4+, no. of e- pairs = 4 + 1/2[5 - 4 - 1] = 4 (sp3 hybridisation)