AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
Bases produce OH⁻ (hydroxide) ions when dissolved in water. Bases that are soluble in water are called alkalis.
The examiner expects two facts in one line: the ion (OH⁻) and the term "alkali." Both parts are needed for full credit. Source passage directly states "Formation of OH⁻(aq) ions in solution is responsible for the basic nature of a substance" and refers to soluble bases as alkalis.