Ncert Exercises & Solutions

8.3: Which of the 3d series of the transition metals exhibits the largest number of oxidation states and why?

Mn (Z = 25) = 3d $^{5}$ 4s $^{2}$

Mn has the maximum number of unpaired electrons present in the d-subshell (5 electrons). Hence, Mn exhibits the largest number of oxidation states, ranging from +2 to +7.