関連ワード:  average atomic mass of carbon    average atomic mass of carbon-12 13 and 14    average atomic mass of carbon isotopes    average atomic mass of carbon calculation    average atomic mass of carbon 12 and 14    average atomic mass of carbon 12    average atomic mass of carbon 12 and 13    average atomic mass of carbon formula    average atomic mass of carbon 13    average atomic mass of carbon is 12.011u