1.oxygen (o) is a gas found in the 16th column of the periodic table. what statement is true about oxygen and the other elements in that column? a. all the elements in the column have similar chemical properties. b.all the elements in the column are in the same period. c.all the elements in the column are nonreactive. d.all the elements in the column have the same number of protons2.why are all of the substances on the periodic table classified as elements? all elements are pure substances. substances on the periodic table cannot be dissolved in water or other liquids. substances on the periodic table can be combined to form compounds and are therefore elements. substances on the periodic table cannot be broken down into other substances and are therefore elements.