Compare the stability of + 2 oxidation state for the elements of the first transition series.

Explanation

The stability of + 2 oxidation state of first row transition metals, in general, decreases from left to right with the exception of Mn and Zn. This is due to increase in the value of the sum of 1st and 2nd ionisation enthalpies. The greater stability of + 2 oxidation states for Mn and Zn are due to half - filled d - subshell `(d^(5))` in `Mn^(2+)` and completely filled d - subshell `(d^(10))` in `Zn^(2+)`.