Which of these ions is smallest in size?

Options

A. `O^(2-)`
B. `C^(4-)`
C. `F^(-)`
D. `N^(3-)`

Answer

C

Explanation

Species having the same number of electrons but different nuclear charge are known as isoelectronic species. The size of such species decreases with increasing nuclear charge because the attraction for the electrons increases.
`{:("",C^(4-),N^(3-),O^(2-),F^(-)),("ionic size",2.6,1.7,1.4,1.36):}`
Thus, `F^(-)` is smallest in size.