balance the following oxidation-reduction reaction and indicate which atoms have under gone oxidation and reduction _hno3+_s. _no+_h2so4

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

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.