Alkali or alkaline-earth metals; rare-earth metals, scandium and yttrium, whether or not intermixed or interalloyed; mercury

280511 Alkali or alkali-earth metals; sodium 280512 Alkali or alkali-earth metals; calcium 280519 Alkali or alkali-earth metals; other than sodium and calcium 280530 Earth-metals, rare; scandium and yttrium, whether or not intermixed or interalloyed 280540 Mercury