"\"Mass fraction\" is used in the construction \"mass_fraction_of_X_in_Y\", where X is a material constituent of Y. It means the ratio of the mass of X to the mass of Y (including X). A chemical or biological species denoted by X may be described by a single term such as \"nitrogen\" or a phrase such as \"nox_expressed_as_nitrogen\". The chemical formula for nitric acid is HNO3."@en . . . . "" . "2019-03-04 17:29:46.0" . "SDN:P07::CF12N399" . . "false" . . "2" . . . "accepted"@en . "2" . . "mass_fraction_of_nitric_acid_in_air"@en . "SDN:P07::CF12N399" . . "2019-03-04 17:29:46.0" . "SDN:P07::CF12N399" .