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

Answer: (A)

BF$_3$ and NO$_2^-$

Answer 2

Explanation:

1. BF 3: The central atom, boron, forms three sigma bonds with fluorine and has no lone pairs. It undergoes sp2 hybridization.
2. NO 2−: The nitrogen atom has three regions of electron density (two sigma bonds and one lone pair). This corresponds to sp2 hybridization.
3. H 2O: The central atom, oxygen, has two sigma bonds and two lone pairs, corresponding to sp3 hybridization.
4. NH 2−: The nitrogen atom forms two sigma bonds and has two lone pairs, corresponding to sp3 hybridization.

Thus, only BF3 and NO2− exhibit sp2 hybridization.

Final Answer: Option (1).