Of the following the one with largest size is

Options

A. `C1^(-)`
B. Ar
C. `K^(+)`
D. `Ca^(2+)`

Answer

A

Explanation

`CI = 18e^(-) = 17p` nuclear charge
`Ar = 18e^(-) = 18p` nuclear charge
`K = 18e^(-) = 19p` nuclear charge
`Ca^(2+) = 18e^(-) = 20p` nuclear charge, and
Nuclear charge `xx(1)/("Ionic radius")`
Out of these Cl has low nuclear energy. Thus, Cl has the largest size among the four ions.