(a) Copper metal shows +1 oxidation state because its electronic configuration is $\left[\mathit{A}\mathit{r}\right]3{\mathit{d}}^{10}4{\mathit{s}}^1$.
It can easily donate one electron from $4{\mathit{s}}^1$ and exhibit +1 oxidation state.
(b) ${\mathit{V}}^{3+}$ and ${\mathit{M}\mathit{n}}^{2+}$ are coloured transition metal because of presence of unpaired electron and shows $\mathit{d}-\mathit{d}$ transition. While ${\mathit{S}\mathit{c}}^{3+}$ and $\mathrm{mathrm}{\mathit{T}\mathit{i}}^{4+}$ are colourless because here $\mathit{d}$-orbitals are empty and there is no $\mathit{d}-\mathit{d}$ transition take place.