Final answer:
A base often exists in the form of hydroxyl ions or bicarbonate ions, which can bind to H+ ions, reducing the solution's acidity and displaying basic properties.
Step-by-step explanation:
A base is often found in the form of a hydroxyl ion (OH−) or a bicarbonate ion (HCO3−) and binds the H+. Bases are substances that release hydroxyl ions in solution, or they may accept H+ ions already present, thus reducing the solution's acidity. An example is the release of bicarbonate, a weak base, in the digestive tract to neutralize the hydrochloric acid from the stomach. According to the Arrhenius definition, the most familiar bases such as NaOH and Ca(OH)2 contain hydroxide ion, OH−, which can accept a proton to form water, thereby displaying their basic properties.