Answer: NaOH (s) Na+ (aq) + OH-(aq)
An Arrhenius acid is any material that ionises when dissolved in water to form the H+ , or hydrogen ions.
An Arrhenius base is any substance that creates the OH–, or hydroxide, ion when dissolved in water.
NaOH is an Arrhenius base because it dissociates in water to produce the hydroxide (OH–) and sodium (Na+ ) ions.