Which of the following does not represents a polyatomic ion?
A polyatomic ion is an ion composed of more than one atoms.
Sulphite, sulphate and phosphate ions are polyatomic as they contain more than one atoms. However, Cl- is a monoatomic ion as it is composed of only chlorine atom. Ions with their formula and charge is given in the following table:
IonFormulaChargeSulphite(SO3)2−-2Sulphate(SO4)2−-2Phosphate(PO4)3−-3Chloride(Cl)−-1