Answer
(a) Na
(b) Cl
(c) Ra
(d) Ne
Work Step by Step
(a) Chlorine is in the third period of the periodic table. The alkali metals are in group 1A of the periodic table. The alkali metal that is in the third period is sodium (Na).
(b) Magnesium is in the third period of the periodic table. The halogens are in group 7A of the periodic table. The halogen that is in the third period is chlorine (Cl).
(c) Masses increase as you go down the periodic table. The alkaline earth metals are in group 2A of the periodic table. The element of group 2A in the lowest position on the periodic table is radium (Ra).
(d) Carbon is in the second period on the periodic table. The halogens are in group 8A of the periodic table. The noble gas that is also in the second period of the periodic table is neon (Ne).
