Ethene, with the formula C2H4, is the first member of the alkene series and is an unsaturated hydrocarbon due to its carbon-carbon double bond. ;
Ethene is the first member of the unsaturated hydrocarbons and the simplest alkene, known for its C-C double bond and trigonal planar structure. ;
Ethene (C₂H₄) is the first member of the alkene series and is classified as an unsaturated hydrocarbon due to its carbon-carbon double bond. Alkenes like ethene have fewer hydrogen atoms compared to alkanes with the same number of carbon atoms. Therefore, the correct answer to the question is D. Unsaturated hydrocarbons.
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