Characteristics of CO3^2- anion:

Bonds of unequal lengths:
- The CO3^2- anion consists of one carbon atom and three oxygen atoms.
- Due to the presence of multiple oxygen atoms, the bonds in the carbonate ion are of unequal lengths.
- The C-O bond lengths are different, with one double bond and two single bonds.

Sp2 hybridisation:
- In the carbonate ion, the carbon atom is sp2 hybridized.
- The three oxygen atoms are attached to the central carbon atom through sigma bonds formed by the overlap of sp2 hybrid orbitals.
- The remaining p orbital on carbon forms a pi bond with one of the oxygen atoms.

Resonance stabilisation:
- The carbonate ion exhibits resonance stabilization due to the delocalization of electrons.
- The double bond can resonate between the carbon and different oxygen atoms, stabilizing the ion.
- This resonance leads to the formation of resonance structures, depicting the distribution of charge density.

Same bond angles:
- The carbonate ion has a trigonal planar molecular geometry.
- The bond angles between the carbon and oxygen atoms are approximately 120 degrees.
- The symmetry of the molecule results in uniform bond angles throughout the carbonate ion.
In conclusion, the CO3^2- anion possesses bonds of unequal lengths, sp2 hybridization of the central carbon atom, resonance stabilization through delocalization of electrons, and uniform bond angles due to its trigonal planar geometry. These characteristics contribute to the stability and properties of the carbonate ion in various chemical reactions.

B,C & D