BECE Science 2023 Paper

Concept:A mixture is two or more substances mixed physically (not chemically combined); each keeps its own properties and they can be separated by physical means.Explanation:Sodium sulphate ($\mathrm{Na_2SO_4}$), hydrogen chloride ($\mathrm{HCl}$) and ammonia ($\mathrm{NH_3}$) are compounds: their elements are chemically combined in fixed proportions.Salt solution is common salt ($\mathrm{NaCl}$) dissolved in water. No reaction takes place, and the salt can be recovered by evaporating the water, so it is a mixture.Answer:Option D (salt solution)