Among the following the pair in which the two species are not isostructural is

Options

A. `BH_4^(-) and NH_4^(+)`
B. `PF_6^(-) and SF_6`
C. `SiF_4 and SF_4`
D. `IO_3^(-) and XeO_3`

Answer

C

Explanation

`SiF_4` has symmetrical tetrahedral shape which is due to `sp^3` hybridization of the central sulphur atom in its excited state configuration. `SF_4` has distorted tetrahedral or Sea- Saw geometry which arise due to `sp^3 d` hybridization of central sulphur atom and due to the presence of lone pair of electron in one of the equatorial hybrid orbital.