Classification Of Elements And Periodicity In Properties Ques 18
18. Identify the correct order of the size of the following:
[2007]
(a) $Ca^{2+}<K^{+}<Ar<Cl^{-}<S^{2-}$
(b) $Ar<Ca^{2+}<K^{+}<Cl^{-}<S^{2-}$
(c) $Ca^{2+}<Ar<K^{+}<Cl^{-}<S^{2-}$
(d) $Ca^{2+}<K^{+}<Ar<S^{2-}<Cl^{-}$
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Answer:
Correct Answer: 18.(a)
Solution:
(a) For isoelectronic species, size of anion increases as negative charge increases whereas size of cation decreases with increase in positive charge. Further ionic radii of anions is more than that of cations. Thus the correct order is
$Ca^{2+}<K^{+}<Ar<Cl^{-}<S^{-}$
BETA
