Question

how many unpaired electron is present in
Fe2+ ion​

Answer 1

Explanation:

4 unpaired electrons

Now since we are given with Iron(II) we take out two electrons from the outermost orbit so as to give the iron a +2 charge. As evident from the configuration, in total there are 4 unpaired electrons. Using the same logic you can count the number of unpaired electrons for any ion.

Answer 2

Electronic configuration of Fe²+ ion is [Ar]3d^6. It has 4 unpaired electrons.

Net electron spin = 4 × $\frac{1}{2}$ = 2