Equal volumes of gaseous, liquid, and solid ethanol do not contain the same number of molecules. Neither do equal volumes of solid water and solid sugar contain the same number of molecules. However, equal volumes of gaseous water and gaseous ethanol have the same number of molecules at the same temperature and pressure. What is different about the gaseous phase of substances that makes Avogadro’s law correct only for gases?

there is none because earth is stationary and flat.

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.