Question

Which of the following species has tetrahedral geometry?

• A. $C{O}_3^{2-}$
• B. $B{H}_4^{-}$
• C. $H_3{O}^{+}$
• D. $N{H}_2^{-}$

Answer 1

The correct option is B $B{H}_4^{-}$

$1.$ The number of hybrid orbitals is the sum of the number of sigma bonds and the number of lone pairs of electrons on central atom.

$2.$ Based on the number of hybrid orbitals, we can find out the hybridization of molecules.

$\text{Molecule}$	$\text{No. of sigma bonds}$	$\text{No. of lone pairs}$	$\text{No. of hybride orbitals}$	$\text{Hybridisation \& Shape}$
$B{H}_4^{-}$	4	0	4	$s{p}^3,\text{Tetrahedral}$
$N{H}_2^{-}$	2	2	4	$s{p}^3,\text{Bent}$
$C{O}_3^{2-}$	3	0	3	$s{p}^2,\text{Planar}$
$H_3{O}^{+}$	3	1	4	$s{p}^3,\text{Pyramidal}$

So, geometry of $B{H}_4^{-}$ is tetrahedral.

Hence, the correct option is $\left(A\right).$