Question: In which of the following pairs the two species are not isostructural ?
$\mathrm{AlF}_{6}^{3-}$ and $\mathrm{SF}_{6}$
$\mathrm{CO}_{3}^{2-}$ and $\mathrm{NO}_{3}^{-}$
$\mathrm{PCl}_{4}^{+}$and $\mathrm{SiCl}_{4}$
$\mathrm{PF}_{5}$ and $\mathrm{BrF}_{5}$
Correct Option: , 4
Solution:
