Which of the following molecules or ions is polar?

Explanation:

1) Carbonate ions( ) is a polar molecule.Polarity of this ion is due to presence of three electro-negative oxygen atoms which will attract shared pair of electrons towards itself which will create negatively charged pole on oxygen and will also induce positively charged pole on carbon atom.

2) Hydrogen cyanide(HCN) is also polar molecule. Polarity of this ion is due to presence of electro-negative nitrogen atom which is bonded to carbon atom  will attract the shared pair of electrons towards itself which will create negatively charged pole on nitrogen atom and will induce positively charged pole on carbon atom.

3) Nitrate ion () is a polar molecule.Polarity of this ion is due to presence of three oxygen atoms. Oxygen is more electro-negative atom than the nitrogen atom which will attract shared pair of electrons towards itself which will create negatively charged pole on oxygen and will also induce positively charged pole on nitrogen atom.