In which of the following molecules/ions $\mathrm{BF}_3, \mathrm{NO}_2^{-}, \mathrm{NH}_2^{-}$and…

In which of the following molecules/ions $\mathrm{BF}_3, \mathrm{NO}_2^{-}, \mathrm{NH}_2^{-}$and $\mathrm{H}_2 \mathrm{O}$, the central atom is $\mathrm{sp}^2$ hybridised ?
  1. $\mathrm{NO}_2^{-}$and $\mathrm{NH}_2^{-}$
  2. $\mathrm{NH}_2^{-}$and $\mathrm{H}_2 \mathrm{O}$
  3. $\mathrm{NO}_2^{-}$and $\mathrm{H}_2 \mathrm{O}$
  4. $\mathrm{BF}_3$ and $\mathrm{NO}_2^{-}$

Solution

Key Idea For $\mathrm{sp}^2$ hybridisation, there must be either $3 \sigma$ bonds or $2 \sigma$ bonds and one lone pair of electrons in the molecule or ions.


Thus, in $\mathrm{BF}_3$ and $\mathrm{NO}_2^{-}$, central atom is $\mathrm{sp}^2$ hybridised.

Asked in: NEET 2009 (Screening)

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