The species `Ar,K^(+)` and `Ca^(2+)` contain the same number of electrons. In which order do their radii increase ?

Options

A. `Ca^(2+) , lt K^(+) lt Ar`
B. `K^(+) , lt Ar lt Ca^(2+)`
C. `Ar lt K^(+) lt Ca^(2+)`
D. `Ca^(2+) lt Ar lt K^(+)`

Answer

A

Explanation

Amongst isoelectronic species higher the + ve charge smaller is the radiius while neutral species has the largest radius . Thus radii increase in the order : `C^(2+) lt K^(+) lt Ar . ` i.e., option (a) is correct .