Question
Which one of the following sets of ions represents the collection of isoelectronic species?
( Atomic nos. : $$F$$ = 9, $$Cl$$ = 17, $$Na$$ = 11, $$Mg$$ = 12, $$Al$$ = 13,
$$K$$ = 19, $$Ca$$ = 20, $$Sc$$ =21 )
A.
$${K^ + },C{l^ - },M{g^{2 + }},S{c^{3 + }}$$
B.
$$N{a^ + },C{a^{2 + }},S{c^{3 + }},{F^ - }$$
C.
$${K^ + },C{a^{2 + }},S{c^{3 + }},C{l^ - }$$
D.
$$N{a^ + },M{g^{2 + }},A{l^{3 + }},C{l^ - }$$
Answer :
$${K^ + },C{a^{2 + }},S{c^{3 + }},C{l^ - }$$
Solution :
$$_{19}{K^ + },{\,_{20}}C{a^{2 + }},{\,_{21}}S{c^{3 + }}{,_{17}}C{l^\_}$$
each contains 18 electrons.