Which of the following are produced when a base is dissolved in water? a. hydronium ions b. hydroxide ions c. hydrogen ions d. ammonium ions

Answer is: B. Hydroxide ions.

An Arrhenius base is a substance that dissociates in water to form hydroxide ions (OH⁻).  

For example sodium hydroxide: NaOH(aq) → Na⁺(aq) + OH⁻(aq).

Another example, balanced chemical reaction: Ba(OH)₂(aq) → Ba²⁺(aq) + 2OH⁻(aq).

According to the Arrhenius definition barium hydroxide is base.

Acids and bases when react (neutralisation) produce salt and water.

water and alcohols have similar properties because water molecules contain hydroxyl groups that can form hydrogen bonds with other water molecules and with alcohol molecules, and likewise alcohol molecules can form hydrogen bonds with other alcohol molecules as well as with water.