9.. on the basis of hybridisation, discuss the structure of :(PCl5),(IF7),(SF6).

Hybridization:

It states that atomic orbitals of slightly different energies combine to form a new set of equivalent orbitals (having the same energy and shape) known as hybrid orbitals.

Geometry of SF₆ based on hybridization:

The geometry of SF₆ molecule can be explained on the basis of sp³d² Hybridization. In SF₆ the central sulphur atom has the ground state configuration, 3s²3p⁴

To account for the hexa valency in SF₆ one electron each from 3s and 3p orbitals is promoted to 3d orbitals. These six orbitals get hybridized to form six sp ³ d²hybrid orbitals. Each of these sp³d² hybrid orbitals overlaps with 2p orbital of fluorine to form S-F bond. Thus, SF₆ molecule has octahedral structure. 

Geometry of PCl₅ based on hybridization:

The five sp³d hybrid orbitals orient themselves in a trigonal bipyramidal manner, which is the geometry of PCl₅. 

Notice that all the P−Cl bonds in the molecule are not equivalent. Three bonds that are present in one plane are called equatorial bonds and have an angle of 120° between them.  

The other two bonds are called axial bonds and are at 90° with the equatorial bonds.

The IF₇ involves sp ³ d ³ hybridisation. The structure is pentagonal bipyramidal.
 

Regards