• # question_answer 69)   Which of the following sets contain only isoelectronic ions? (a) $\text{Z}{{\text{n}}^{\text{2+}}}\text{,C}{{\text{a}}^{\text{2+}}}\text{,G}{{\text{a}}^{\text{3+}}}\text{,A}{{\text{l}}^{\text{3+}}}$                                                (b) ${{\text{K}}^{\text{+}}}\text{,C}{{\text{a}}^{\text{2+}}}\text{,S}{{\text{c}}^{\text{3+}}}\text{,C}{{\text{l}}^{\text{-}}}$ (c) ${{P}^{3-}},{{S}^{2-}},C{{l}^{-}},{{K}^{+}}$                                                    (d) $T{{i}^{4+}},Ar,C{{r}^{3+}},{{V}^{5+}}$

(b, c) The ions having same number of electrons are called isoelectronic ions. ${{K}^{+}},C{{a}^{2+}},S{{c}^{3+}},C{{l}^{-}}$ ions have 18 electrons each. ${{P}^{3-}},{{S}^{2-}},C{{l}^{-}},{{K}^{+}}$ ions have 18 electrons each.