All the bonds in `SF_(4)` are not equivalent. Why ?

Explanation

S in `SF_(4)` is `sp^(3)` d-hybridized. Therefore, `SF_(4)` has trigonal bipyramid structure or see-saw geometry. Two of the S-F bonds occypy equatorial positions and are 155 pm long while the third equatorial position is occupied by a lone pair of electrons. The remaining two S-F bonds occypy axial positions and are little longer (165 pm) due to repulsions between the axial bond pairs and the equatorial lone pair. Thus, all the four S-F bonds in `SF_(4)` are not equivalent.