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

From the following pairs of ions which one is not an iso-electronic pair?
  1. O2-,F-
  2. Na+,Mg+2
  3. Mn2+,Fe3+
  4. Fe2+,Mn2+

Solution

1) O2-,F- Both have 10 electrons
2) Na+,Mg+2 Both have 10 electrons
3) Mn2+,Fe+3 Both have 23 electrons
4) Mn2+ has 23 electrons while, Fe+2 have 24 electrons so, they are not an iso-electronic pair.

Asked in: NEET 2021

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