In which of the following pairs , the two species are not isostructural ? `PCl_4^(+)` and `SiCl_4`, `PF_5` and `BrF_5`, `AlF_6^(3-)` and `SF_6`, `CO_3^(2-)` and `NO_3^(-)`

Options

A. `CO_3^(2-)` and `NO_3^(-)`
B. `PCl_4^(+)` and `SiCl_4`
C. `PF_5` and `BrF_5`
D. `AlF_6^(3-)` and `SF_6`

Answer

C

Explanation

`CO_3^(2-)` and `NO_3^(-)` both are trigonal planar, `PCl_4^(+)` and `SiCl_4` both are tetrahedral, `PF_5` is `sp^3d` hybridized and the shape is trigonal bipyramidal, whereas `BrF_5` is `sp^3d^2` hybridized and its shape is square pyramidal. `AlF_6^(3-)` and `SF_6` both are octahedral.