Chapter 17, Problem 17.137SP

Give a method for separating the following pairs of ions by the addition of no more than two substances.
(a) $H{g}_2{}^{2+}andC{o}^{2+}$   (b) $N{a}^{+}andM{g}^{2+}$
(c) $F{e}^{2+}andH{g}^{2+}$   (d) $B{a}^{2+}andP{b}^{2+}$