Question

An ab4 molecule has two lone pairs of electrons on the a atom (in addition to the four b atoms). what is the electron-domain geometry around the a atom?

Answer 1

In the given system, A is the central atom which is surrounded by four B atoms and forms 4 covalent bonds. Ideally, this structure could correspond to a square planar molecular geometry. However, there are two lone pairs of electrons on the central atom A which must be considered in order  interpret the electron geometry.

Thus the electron domain geometry around A is octahedral

Answer 2

Answer : The electron-domain geometry around the 'A' atom is, octahedral.

Explanation :  

As per given in the question, an $AB_4$ has two lone pairs of electrons on the atom 'A' and four number of monovalent atoms (B) are bonded to the central atom.

That means, the total number of electrons pairs = 2 + 4 = 6

The number of electrons pairs is 6 that means the hybridization will be $sp^3d^2$ and the electronic or electron domain geometry of the molecule will be octahedral.

The electron domain geometry is also shown below.

Hence, the electron-domain geometry around the 'A' atom is, octahedral.