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

Options

A. `SiF_(4) and SF_(4)`
B. `IO_(3)^(-) and XeO_(3)`
C. `BH_(4)^(-) and NH_(4)^(+)`
D. `PF_(6)^(-) and SF_(6)`

Answer

A

Explanation

Shape (structure) of a species can be predicted on the basis of hybridisation of its central atom, which in turn can bonds (H) be known by determining the number of hybrid.
Thus `H=(1)/(2)=(V+X-C+A)`
For `SiF_(4): H=(1)/(2)(4+4-0+0)=4,sp^(3)` (Tetrahedral structure)
For `SF_(4): H=(1)/(2)(6+4-0+0)=5,sp^(3)d` (see-saw structure due to presence of one lp of electrons on central atom)
Hence the two compounds have different structures.