Solution:Concept- Hydroxyl ion is formed along with hydronium ions as a result of dissociation of water molecules.
The dissociation of water molecules can be shown as-
The hydroxyl ion is and the hydronium ion is . Hydroxyl ion is also called hydroxide ion.It consists of a hydrogen and an oxygen atom held together by a covalent bond. Hydrogen carries a negative electrical charge.
Hence, the correct answer is 2.