Regents Chemistry Exam August 2022
38 Given the diagram representing a classification of matter:
Which types of matter are represented by X and Z in the diagram?
(1) X is mixture, and Z is substance.
(2) X is substance, and Z is mixture.
(3) X is element, and Z is compound.
(4) X is compound, and Z is element.
Explanation: A pure substance consists of one element or one compound while a mixture consists of two or more elements or compounds. Elements can be found on the periodic table. We can see that Fe is an element and should belong to the substance category. CaCO3 is a compound (two or more elements in fixed proportions) and should be under the substance category as well. Air, on the other hand, consists of different substances : oxygen, carbon dioxide, nitrogen and many more and should belong to the mixtures category. NaCl(aq) is sodium chloride dissolved in water and represents a mixture as well (two substances: sodium chloride and water).