Among the following the pair in which the two species are not isostuctural 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 ascertained on the basic pf hybridisation of its central atom , which in turn can be known by determinimg the number of hybrid bonds (H) .
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)
Hence the two compounds have structures.