Question

In which one of the following pairs the central atoms exhibit sp$^2$ hybridization?

• A. BF$_3$ and NO$_2^-$
• B. NH$_2^-$ and H$_2$O
• C. H$_2$O and NO$_2$
• D. NH$_2^-$ and BF$_3$

Answer 1

The Correct Option is A

To identify molecules with central atoms exhibiting sp² hybridization, each molecule is analyzed:

1. BF₃ (Boron Trifluoride):
   • The central boron atom in BF₃ is bonded to three fluorine atoms.
   • Boron's three valence electrons are used to form three B-F sigma bonds.
   • Therefore, boron in BF₃ displays sp² hybridization due to three sigma bonds and no lone pairs.
2. NO₂^- (Nitrite Ion):
   • The nitrogen atom in NO₂^- carries a formal negative charge, resulting in three electron domains.
   • With two single bonds and one lone pair, the nitrogen atom requires sp² hybridization to accommodate these three electron domains.
3. NH₂^- (Amide Ion):
   • The nitrogen atom in NH₂^- is bonded to two hydrogen atoms and possesses two lone pairs.
   • To accommodate these four electron domains, the nitrogen atom undergoes sp³ hybridization.
4. H₂O (Water):
   • The oxygen atom in H₂O is bonded to two hydrogen atoms and has two lone pairs, totaling four electron domains.
   • This configuration necessitates sp³ hybridization for the oxygen atom.
5. NO₂ (Nitrogen Dioxide):
   • Nitrogen in NO₂ forms two sigma bonds and one lone pair, analogous to NO₂^-, thus utilizing sp² hybridization.

Based on this analysis, the molecules with central atoms exhibiting sp² hybridization are BF₃ and NO₂^-.

Consequently, the correct answer is:

BF₃ and NO₂^-