## Chemistry: The Science in Context (4th Edition)

The alkali metals are in group 1 of the periodic table. Option (b) is incorrect. Chlorine (Cl$_{2}$) is a halogen in group 17. Option (c) is incorrect. Xenon (Xe) is a noble gas in group 18. Option (d) is incorrect. Bromine (Br$_{2}$) is a halogen in group 17. Option (a) is correct. Sodium (Na) is an alkali metal in group 1 of the periodic table.