What are the different possible oxidation states exhibited by scandium $(Sc)$?

The electronic configuration (outermost) of $Mn^{2+}$ ion (atomic number of $Mn = 25$) in its ground state is

Observe the following ions: $V^{2+}, Zn^{2+}, Cu^{2+}, Fe^{2+}, Fe^{3+}, Ti^{3+}, Sc^{3+}, Ti^{4+}, Ni^{3+}, Co^{3+}, Cu^+$. How many ions in the above list have zero magnetic moment?

The $3d$ elements show variable oxidation states because the energies of the following sets of orbitals are almost similar:

The melting point of $Zn$ is lower as compared to those of the other elements of the $3d$ series because:

What is the difference in atomic volume between $Au$ and $Cu$ in $22$ carat gold jewelry?