From the following pairs of ions which one is not an iso-electronic pair?

Options

A. `Na^(+),Mg^(2+)`
B. `Mn^(2+),Fe^(3+)`
C. `Fe^(2+),Mn^(2+)`
D. `O^(2-),F^(-)`

Answer

C

Explanation

`Fe^(+2)andMn^(+2)` are not iso-electronic.