No. of unpaired electrons
23V2+24Cr2+25Mn2+26Fe2+18[Ar]4S03d318[Ar]4S03d418[Ar]4S03d518[Ar]4S03d6=3=4=5=4
On moving left to right in the periodic table, ionic size decreases.
Sc shows only one oxidation state, and it is +3 but Mn shows variable oxidation state from +2 to +7.