When K2Cr2O7 is cooled from 80oC to 20oC, how much solute will precipitate out of the solution?

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.