Answer
(a) 13
(b) 3
(c) 2
Work Step by Step
Use the periodic table inside the front cover.
Of the 18 elements in the fourth period (row), 13 (potassium thru gallium) are metals, colored gray or blue; three (selenium, bromine, krypton) are nonmetals, colored purple; and two (germanium and arsenic) are metalloids, colored orange.
