Question

Which of the following pairs are isostructural

$\left(A\right).TiC{l}_4,SiC{l}_4$

$\left(B\right).S{O}_3^{2-},Cr{O}_3^{2-}$

$\left(C\right).N{H}_3,N{O}_3^{-}$

$\left(D\right).Cl{F}_3,BC{l}_3$

• A. A, B
• B. A, C
• C. B, C
• D. A, D

Answer 1

The correct option is A A, B

Answer: (a)

Isostructural compounds are those that have the same structure as well as same hybridisation.

In case (B), the structure of $S{O}_4^{2-}$is tetrahedral as it has 4σ bonds and zero lone pairs on the central atom. Similarly, $Cr{O}_4^{2-}$ also has 4σ bonds and zero lone pairs on the central atom. According to VSEPR, the structures of $S{O}_4^{2-}$ and $Cr{O}_4^{2-}$ are:

Hence, we can say, $S{O}_4^{2-}$ and $Cr{O}_4^{2-}$ are isostructural.

In case (A), $TiC{l}_4$ has 4σ bonds and zero lone pairs on the central atom. Hence, it is tetrahedral. Similarly, $SiC{l}_4$ is also tetrahedral.

Hence, $TiC{l}_4$ and $SiC{l}_4$ are also isostructural.

In case (C), NH₃ has 3σ bonds and 1 lone pair of electrons around nitrogen. Thus, according to VSEPR, NH₃ has a pyramidal structure. In $N{O}_3^{-}$, the nitrogen atom has 3 bonds and no lone pair of electrons. Thus, it is trigonal planar. According to VSEPR, the structures of NH₃ and NO^-₃ are:

Hence, $N{H}_3$ and $N{O}_3^{-}$ are not isostructural.

In case (D), ClF₃ has 3 σ and 2 lone pairs on the central atom. Its structure is distorted T shaped (but geometry is trigonal bipyramidal). BCl₃ has 3 σ bonds and no lone pair on the B atom. Thus, it is trigonal planar.

Hence, ClF₃ and BCl₃ are not isostructural.