The geometry of a complex species can be understood from the knowledge of the type of hybridization of orbitals of the central atom. The hybridization of orbitals of a central atom in [B(OH4)]- and the geometry of the complex are respectively

1. sp3, tetrahedral

2. sp3, square planar

3. sp3d2, octahedral

4. dsp2, square planar



Hint: The geometry of boron in [B(OH)4]- is tetrahedral.

Structure of [B(OH4)]- is