Answer
(a) K$^{1+}$
(b) Br$^{1-}$
(c) Ba$^{2+}$
(d) S$^{2-}$
Work Step by Step
(a) K$^{1+}$
The elemental symbol for potassium is K. Potassium is in group 1; therefore, it has a valence of 1+.
(b) Br$^{1-}$
The elemental symbol for bromine is Br. Bromine is in group 17; therefore, it has a valence of 1-.
(c) Ba$^{2+}$
The elemental symbol for barium is Ba. Barium is in group 2; therefore, it has a valence of 2+.
(d) S$^{2-}$
The elemental symbol for sulfur is S. Sulfur is in group 16; therefore, it has a valence of 2-.
