JAMB Chemistry 2011 Paper

Concept:Deliquescent compounds absorb moisture from the air and dissolve in the absorbed water to form a solution.Explanation:Among the options, calcium chloride ($\mathrm{CaCl}_2$) is well known as a deliquescent substance.It absorbs atmospheric water vapour and eventually forms a liquid solution.Sodium nitrate ($\mathrm{NaNO}_3$) is not deliquescent under normal conditions.Copper(II) oxide ($\mathrm{CuO}$) is an insoluble oxide and does not absorb moisture.Sodium carbonate decahydrate ($\mathrm{Na}_2\mathrm{CO}_3 \cdot 10\mathrm{H}_2\mathrm{O}$) is efflorescent, losing its water of crystallization, not deliquescent.Therefore, the deliquescent compound is calcium chloride.Answer:B. $\mathrm{CaCl}_2$