In which one of the following paris the radius of the second species is greater than that of the first?

Options

A. a) Na, Mg
B. b)`O^(2-), N^(3-)`
C. c)`Li^(+), Be^(2+)`
D. `d) Ba^(2+), Sr^(2+)`

Answer

B

Explanation

`O^(2-) and N^(3-)` both are isoelectronic but differ in the charge possessed by them. As the negative charge increase, the electrons are held less and less tightly by the nucleus, therefore, increase radius from `O^(2-)` to `N^(3-)`.