WAEC Chemistry 2021 Paper

Concept:The solubility of a gas in water depends on its polarity and its ability to form hydrogen bonds with water.Explanation:Ammonia ($\mathrm{NH}_3$) is a highly polar gas.It forms strong hydrogen bonds with water molecules.It also reacts with water to form ammonium hydroxide, making it extremely soluble.Carbon (IV) oxide ($\mathrm{CO}_2$), chlorine ($\mathrm{Cl}_2$), and nitrogen ($\mathrm{N}_2$) are either non-polar or weakly polar.They do not form hydrogen bonds with water and are only slightly soluble at room temperature.Hence, ammonia is the gas that is highly soluble in water.Answer:A. ammonia