In which of the following pairs of molecules/ ions, the central atoms have `sp^2`-hybridization ?

Options

A. `NO_2^-` and `NH_3`
B. `BF_3` and `NO_2^-`
C. `NH_2^-` and `H_2O`
D. `BF_3` and `NH_2^-`

Answer

B

Explanation

Key Idea For `sp^3` hybridisation , there must be `3 sigma` bonds or `2 sigma` bonds along with a lone pair of electrons.
`(i)NO_2^(-) rArr 2 sigma + 1 lp =3 i.e. sp^2` hybridisation
`(ii)NH_3 rArr 3 sigma + 1 lp =4 i.e. sp^3` hybridisation
`(iii)BF_3 rArr 3 sigma + 0 lp =3 i.e. sp^2` hybridisation
`(iv)NH_2^(-) rArr 2 sigma + 2 lp =4 i.e. sp^3` hybridisation
`(v)H_2O rArr 2 sigma + 2 lp =4 i.e. sp^3` hybridisation
Thus , among the given pairs, only `BF_3` and `NO_2^-` have `sp^2` hybridisation.