Why is that in the `SF_(4)` molecule, the lone pair of electrons occupies an equatorial position in the overall trigonal pyramidal arrangement in preferencr to an axial position ?

Explanation

The two possible structures of `SF_(4)` molecule are as follows:

In the structure (i), the lone pair is in the exial position which leads to three lp-bp repulsions at `90^(@).` In the structure (ii), the lone pair is in the equatoral position and there are only two lp-bp repulsions at `90^(@).` Hence, strucutre (ii), i.e., lp at equational position is preferred to the axial position.