Which of the following compounds will undergo polymerization reaction?

Explanation: Addition polymerization requires an unsaturated molecule (usually an alkene) with a C=C double bond. Among the options, only \(\mathrm{C_2H_4}\) (ethene) has a double bond, so it readily forms poly(ethene):

\(n\,\mathrm{CH_2{=}CH_2} \;\rightarrow\; \mathrm{(-CH_2-CH_2-)_n}\)

• \(\mathrm{C_2H_6}\) (ethane): saturated—does not undergo addition polymerization.
• \(\mathrm{C_2H_5OH}\) (ethanol) and \(\mathrm{C_2H_5COOH}\) (a carboxylic acid): single-functional; they don’t polymerize by themselves (condensation polymers need di-functional monomers).