determine the percent change in optimum recommended fluoride concentration for water system with annual average maximum daily temperatures of 10.0 to 12.0 celsius the percent change is given by

im not exactly sure but i think its b!

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.