NEET 2016 Physics and Chemistry Paper 2

1. CO32− and SO32− :
- CO32− : Carbonate ion has 4(C)+3×6(O)+2 (charge) =24 electrons.
- SO32− : Sulfite ion has 6(S)+3×6(O)+2 (charge) =26 electrons.
- These ions are not isoelectronic.
2. ClO3−and CO32− :
- ClO3−: Chlorate ion has 7(Cl)+3×6(O)+1 (charge) =26 electrons.
- CO32− : Carbonate ion has 24 electrons.
- These ions are not isoelectronic.
3. SO32− and NO3−:
- SO32− : Sulfite ion has 26 electrons.
- NO3−: Nitrate ion has 5(N)+3×6(O)+1 (charge) =24 electrons.
- These ions are not isoelectronic.
4. ClO3−and SO32− :
- ClO3−: Chlorate ion has 26 electrons.
- SO32− : Sulfite ion has 26 electrons.
- These ions are isoelectronic.
- Both ions have a trigonal pyramidal structure.
- These ions are isostructural.
Therefore, the correct pair is ClO3−and SO32−.