The density of a concentrated phosphoric acid solution is 1.576 g/ml solution at 20°C. It contains 138.0 g H, PO4 per 1.00E+2ml of solution​

b. examine and describe cells

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.