. "accepted"@en . "Mass concentration means mass per unit volume and is used in the construction mass_concentration_of_X_in_Y, where X is a material constituent of Y. A chemical 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 ethene is C2H4. Ethene is a member of the group of hydrocarbons known as alkenes. There are standard names for the alkene group as well as for some of the individual species."@en . "" . . "2009-07-06 15:41:29.0" . "SDN:P07::CF12N255" . . "2009-07-06 15:41:29.0" . "SDN:P07::CF12N255" . "1" . "false" . . . . "SDN:P07::CF12N255" . . "1" . "mass_concentration_of_ethene_in_air"@en . .