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

1.	s-Orbital is becoming more and more half-filled.
2.	f-Orbital is becoming more and more half-filled.
3.	d-Orbital is becoming more and more half-filled. ​​​​​
4.	p-Orbital is becoming more and more half-filled.

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 :  

Which d-block elements are not considered transition elements, and why?

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 ${\mathrm{Mn}}^{3+},$ ${\mathrm{Cr}}^{3+},$ ${\mathrm{V}}^{3+,}$ $\mathrm{and}$ ${\mathrm{Ti}}^{3+\hspace{0.17em}}$ are, respectively:

Alloy that contains lanthanoid metals is-