Question

Which of the following are isostructural pairs ? (Note: Based on typical JEE pairs like $SO_4^{2-}$ and $BF_4^-$ or $NH_3$ and $PH_3$)

• A. A and B only
• B. A and C only
• C. B and C only
• D. C and D only

Hint:

To determine if molecules are isostructural, calculate the steric number (Lone pairs + Bonded atoms). If they have the same number of valence electrons and central atoms from the same group, they are usually isostructural.

Answer 1

The Correct Option is A

Step 1: Isostructural pairs have the same hybridisation and the same molecular geometry (shape).
Step 2: For example, $NO_3^-$ and $CO_3^{2-}$ are both $sp^2$ hybridised and trigonal planar.
Step 3: $NF_3$ and $H_3O^+$ are both $sp^3$ hybridised and pyramidal.