Which polyatomic ion is found in the compound represented by the formula NaHCO3?
(1) acetate (3) hydrogen sulfate
(2) hydrogen carbonate (4) oxalate

Answer is (2) - hydrogen carbonateExplanation:NaHCO₃ is an ionic compound which is made from Na⁺ and HCO₃⁻ ions. The decomposition is NaHCO₃ → Na⁺ + HCO₃⁻ Among the resulted ions, Na⁺ is a monatomic ion while HCO₃⁻ is a polyatomic ion. Polyatomic ions mean ions which are made of two or more different atoms.HCO₃⁻ is made from 3 atoms as H, C and O. The name of HCO₃⁻ ion is bicarbonate or hydrogen carbonate.