According to the ideal gas law, a 9.742 mol sample of methane gas in a 0.8095 L container at 500.9 K should exert a pressure of 494.7 atm. What is the percent difference between the pressure calculated using the van der Waals' equation and the ideal pressure? For CH4 gas, a = 2.253 L2atm/mol2 and b = 4.278×10-2 L/mol.

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.  

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