D And F Block Elements

Ionic compounds of $\mathrm{Sc}^{3+}$ and $\mathrm{Cu}^{+}$are coloured because of $\mathrm{d}-\mathrm{d}$ electronic transitions

The order in which the paramagnetic nature of the 4 cations $\mathrm{Cr}^{2+}, \mathrm{Mn}^{2+}, \mathrm{V}^{2+}$ and $\mathrm{Fe}^{2+}$ vary is $\mathrm{V}^{2+}<\mathrm{Cr}^{2+}=\mathrm{Mn}^{2+}<\mathrm{Fe}^{2+}$

As the oxidation number of the transition element increases, the ionic nature decreases and the oxides show acidic nature predominantly

The metal Cobalt has the electronic configuration $[\mathrm{Ar}] 3 \mathrm{~d}^5$ in the +3 oxidation state