Which of the following statements regarding lanthanides is not correct?

Except ${ }_{57}{\mathrm{La}}^{3+}{,}_{58}{\mathrm{Ce}}^{4+}$ and ${ }_{71}{\mathrm{Lu}}^{3-}$ salts, all other compounds of lanthanides are paramagnetic

The compounds formed by lanthanides are covalent

The colour of the compound of lanthanide element having xf electrons is often similar to that of the element having $( 14 - \mathrm{x} )\mathrm{f}$ electrons

The pairs ${ }_{40}\mathrm{Zr}$ and ${ }_{72}\mathrm{Hf}{,}_{41}\mathrm{Nb}$ and ${ }_{73}\mathrm{Ta}$, and ${ }_{42}\mathrm{Mo}$ and ${ }_{74}\mathrm{W}$ have nearly identical sizes