sentences: krypton belongs to noble gases family , group 18 on the periodic table
docs: krypton is gas. krypton is chemical_element. krypton_difluoride is chemical_compound. krypton is noble_gas. kryptonite is solid. krypton is non_metallic_element. kryptonite is natural_inanimate_thing. one_of_chemical_elements is krypton.