The increasing order of the ionic radii of the given isoelectronic species is-

Options

A. `S^(2-),Cl^(2-),Ca^(2+),K^(+)`
B. `Ca^(2+),K^(+),Cl^(-),S^(2-)`
C. `K^(+),S^(2-),Ca^(2+),Cl^(-)`
D. `Cl^(-),Ca^(2+),K^(+),S^(2-)`.

Answer

B

Explanation

For any atom or ion, ionic radius `prop(e//Z)` [e=number of electrons and Z=atomic number]. Since the given ions are isoelectronic their electron number is also same. It means higher the atomic number lower will be the ionic radius of the ion. Therefore, the correct order of the ionic radii of the ions is `Ca^(2+) lt K^(+) lt Cl^(-) lt S^(2-)`.