The correct order of the decreasing ionic radii among the following isoelectronic species are :

Options

(a) Ca²⁺ > K⁺ > S²⁻ > Cl⁻
(b) Cl⁻ > S²⁻ >Ca²⁺ > K⁺
(c) S²⁻ > Cl⁻ >K⁺ >Ca²⁺
(d) K⁺ > Ca²⁺ > Cl⁻ > S²⁻

Correct Answer:

S²⁻ > Cl⁻ >K⁺ >Ca²⁺

Explanation:

Among the isoelectronic species, size increases with the increase in negative charge. Thus S has the highest negative charge and hence largest in size followed by Cl, K and Ca