Question

The species Ar, K+ and Ca2+ contain the same number of electrons. In which order do their radii increase?

(a) Ca2+ < K+ < Ar

(b) K+ < Ar < Ca2+

(c) Ar < K+ < Ca2+

(d) Ca2+ < Ar < K+

Answer 1

The correct option is : (a) Ca2+ < K+ < Ar

Explanation :

In case of isoelectronic species, radius decreases with increase in nuclear charge.