Among the species given identify the isostructural pairs (have same structure)A [NF3 and BF3] B C [BCl3 and BrCl3] D [NH3 and H2O]

The structure of a molecule is determined by the number of electron pairs in its valence shell. These electron pairs can be bonding pairs or lone pairs. The structure is determined by the repulsion between these electron pairs according to VSEPR theory.

1. [NF3 and BF3]: NF3 has a trigonal pyramidal structure because it has 3 bonding pairs and 1 lone pair of electrons. On the other hand, BF3 has a trigonal planar structure because it has 3 bonding pairs and no lone pairs. So, they are not isostructural.

2. [BCl3 and BrCl3]: BCl3 has a trigonal planar structure with 3 bonding pairs and no lone pairs. BrCl3 has a T-shaped structure because it has 3 bonding pairs and 2 lone pairs. So, they are not isostructural.

3. [NH3 and H2O]: NH3 has a trigonal pyramidal structure because it has 3 bonding pairs and 1 lone pair. H2O has a bent or V-shaped structure because it has 2 bonding pairs and 2 lone pairs. So, they are not isostructural.

Therefore, none of the given pairs are isostructural.