Please answer these three questions :( 1) 6 K3PO4 + HCl ---> KCl + H3PO4

2) Na2O2 + H2O > NaOH

3) NaCl +___F2 > NaF + Cl2

"the periodic table is arranged in order of atomic number."

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.