Which of the following species has tetrahedral geometry?
A. BH^-₄

B. NH^-₂

C. CO₃^2-

D. H₃ O⁺

The shape of all the compounds can be calculated from hybridization, which can be determined by the application of formula:

H = number of orbitals involved in hybridization
V= valence electrons of a central atom
M= number of monovalent atoms linked with the central atom
C = charge on the cation
A = charge on the anion

Thus, the shape of all molecules are

BH^-₄ is tetrahedral, NH^-₂ is V-shape, CO₃^2- is triangular planar and H₃ O⁺ is pyramidal.