sentences: the earth 's atmosphere is made of 78 percent nitrogen by mass
docs: composition_of_earth is 28_percent_oxygen. atmosphere is mostly_nitrogen. composition_of_earth is 2.7_percent_nickel. nitrogen is gas_at_1_atmosphere. world has oxygen_and_nitrogen_atmosphere earth is 35_percent_iron. earths_atmosphere has nitrogen composition_of_earth is 17_percent_magnesium. composition_of_earth is 35_percent_iron. composition_of_earth is 12.7_percent_nickel.