Calculate the value of the equilibrium constant Kc for this reaction. Round your answer to 2 significant digits.

it's c. elements are placed in rows based on how may valencies electrons have.

answer///carbon;

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.