Answered

When dissolved in water, an Arrhenius base yields(1) hydrogen ions (2) hydronium ions(3) hydroxide ions (4) oxide ions



Answer :

When dissolved in water, an Arrhenius base yields "(1) hydrogen ions" although it should be noted that this car vary somewhat depending on the extent of the reaction. 
transitionstate

Answer:

               Hydroxide Ions

Explanation:

                   Acid and Bases are defined according to three different theories and concepts.

                      A)  Arrhenius Concept

                      B) Lowry Bronsted Theory

                       C) Lewis Theory

According to Arrhenius Concept of Acid and Base, "Acid is any specie which when dissolved in water ionizes to produce H⁺ ions".

Examples:

                                  HNO₃   →    H⁺  +  NO₃⁻

                                  H₃PO₄    →    3 H⁺  +  PO₄³⁻

While, "Bases are those species which when dissolved in water produces Hydroxyl Ions (OH⁻)".

Examples:

                                  KOH    →  K⁺  +  OH⁻

                                  Ca(OH)₂    →     Ca²⁺  +  2 OH⁻