![\[\left( \mathbf{i} \right)\text{ }\mathbf{Z}{{\mathbf{n}}^{\mathbf{2}+}},\text{ }\mathbf{C}{{\mathbf{a}}^{\mathbf{2}+}},\text{ }\mathbf{G}{{\mathbf{a}}^{\mathbf{3}+}},\text{ }\mathbf{A}{{\mathbf{l}}^{\mathbf{3}+}}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-f9b656c6f512de0f78f5c9e95ea9e1bc_l3.png "Rendered by QuickLaTeX.com")
![\[\left( \mathbf{ii} \right)\text{ }{{\mathbf{K}}^{+}},\text{ }\mathbf{C}{{\mathbf{a}}^{\mathbf{2}+}},\text{ }\mathbf{S}{{\mathbf{c}}^{\mathbf{3}+}},\text{ }\mathbf{C}{{\mathbf{l}}^{}}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-02a8f827fa33900690bdb99cc37e81aa_l3.png "Rendered by QuickLaTeX.com")
![\[\left( \mathbf{iii} \right)\text{ }{{\mathbf{P}}^{\mathbf{3}-}},\text{ }{{\mathbf{S}}^{\mathbf{2}-}},\text{ }\mathbf{C}{{\mathbf{l}}^{}},\text{ }{{\mathbf{K}}^{+}}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-9e135ccca95537425808d01a2026aa19_l3.png "Rendered by QuickLaTeX.com")
![\[\left( \mathbf{iv} \right)\text{ }\mathbf{Ti}{{~}^{\mathbf{4}+}},\text{ }\mathbf{Ar},\text{ }\mathbf{C}{{\mathbf{r}}^{\mathbf{3}+}},\text{ }{{\mathbf{V}}^{\mathbf{5}+}}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-31b52550d9bb732119e63c874ec47f83_l3.png "Rendered by QuickLaTeX.com")
Option (ii) and (iii) are the answers.
(i) Zn2+ (30 – 2 = 28), Ca2+ (20 – 2 = 18), Ga3+ (31-3= 28), Al3+ (13 – 3 = 10) are not isoelectronic.
(ii) K+ (19 – 1 = 18), Ca2+ (20 – 2 = 18), Sc3+ (21 – 3 = 18), Cl– (17 + 1 = 18) are isoelectronic.
(iii) P3- (15 + 3 = 18), S2- (16 + 2 = 18), Cl– (17 + 1 = 18), K+ (19 – 1 = 18) are isoelectronic.
(iv) Ti4+ (22 – 4 = 18), Ar (18), Cr3+ (24 – 3 = 21), V5+ (23 – 5 = 18) are not isoelectronic.