Mn²⁺ compounds are more stable than Fe²⁺ compounds towards oxidation in their +3 state because :

The +2 oxidation state becomes more stable in the first half of the first-row transition elements with increasing atomic number because:

The oxo metal anions of the 3d series in which the metal exhibits an oxidation state equal to its group number is /are -

The consequence(s) of lanthanoid contraction is/are :  

The d-block elements that may not be regarded as transition elements are :

The different oxidation states exhibited by the lanthanoids are:

The "Disproportionation" reaction means that :

In the 3d series, a metal with a +1 oxidation state is:

The number of unpaired electrons in the gaseous ions ${\mathrm{Mn}}^{3+},$ ${\mathrm{Cr}}^{3+},$ ${\mathrm{V}}^{3+,}$ $\mathrm{and}$ ${\mathrm{Ti}}^{3+ }$ are, respectively: