Final answer:
Calcium hydroxide is considered a strong base because all the calcium hydroxide that dissolves in water completely ionizes, resulting in the formation of hydroxide ions and calcium ions in a 1:2 ratio.
Step-by-step explanation:
Calcium hydroxide forms very few hydroxide ions in solution, but it is still considered a strong base because b) All the calcium hydroxide in solution ionizes. While calcium hydroxide, Ca(OH)2, is relatively insoluble in water, it is large enough that its solutions are basic. As a strong base, it nearly 100% dissociates into ions when it dissolves in water. This means that for the portion that does dissolve, it dissociates completely into calcium ions (Ca2+) and hydroxide ions (OH-) in a 1:2 ratio, given its chemical formula. Therefore, despite being sparingly soluble, the solubility does not affect its classification as a strong base; rather, it is the complete dissociation of the dissolved part that is crucial.