Answer:
3. Shared and unshared electron pairs repel each other as much as
possible
Step-by-step explanation:
The variations in the bond angles of molecules and ions can be explained using the valence shell electron pair repulsion theory.
The VESPR model determines the total number of electron pairs (TEP) surrounding the central atom of a specie. The TEP consists of bond pairs BP and lone pairs LP.
All the electron pairs will orient themselves in such a way as to minimize the electrostatic repulsion between them.
The repulsion determines the geometry of the covalent bonds around the central atom. As the number of lone pairs increases from 0 to 2, the bond angles diminishes progressively.