Question

Which of the following sets contain only isoelectronic ions?

(i) \[\ce{Zn^{2+}, Ca^{2+}, Ga^{3+}, Al^{3+}}\]

(ii) \[\ce{K+ , Ca^{2+}, Sc^{3+}, Cl-}\]

(iii) \[\ce{P^{3-}, S^{2-}, Cl- , K+}\]

(iv) \[\ce{Ti^{4+}, Ar, Cr^{3+}, V^{5+}}\]

Answer 1

(ii) \[\ce{K+ , Ca^{2+}, Sc^{3+}, Cl-}\]

(iii) \[\ce{P^{3-}, S^{2-}, Cl- , K+}\]

Explanation:

(a) \[\ce{Zn^{2+}}\] (30 – 2 = 28), \[\ce{Ca^{2+}}\] (20 – 2 = 18), \[\ce{Ga^{3+}}\] (31 – 3 = 28), \[\ce{Al^{3+}}\] (13 – 3 = 10) are not isoelectronic.

(b) \[\ce{K+}\] (19 – 1 = 18), \[\ce{Ca^{2+}}\] (20 – 2 = 18), \[\ce{Sc^{3+}}\] (21 – 3 = 18), \[\ce{Cl-}\] (17 + 1 = 18) are isoelectronic.

(c) \[\ce{P^{3-}}\] (15 + 3 = 18), \[\ce{S^{2-}}\] (16 + 2 = 18), \[\ce{Cl-}\] (17 + 1 = 18), K+ (19 – 1 = 18) are isoelectronic.

(d) \[\ce{Ti^{4+}}\] (22 – 4 = 18), \[\ce{Ar}\] (18), \[\ce{Cr^{3+}}\] (24 – 3 = 21), \[\ce{V^{5+}}\] (23 – 5 = 18) are not isoelectronic.