Number of isomers possible with the formula, C₂H₄O is 

Total number of isomers = 3 ;

Total number of structural isomers = 3 ;

Total number of isomeric aldehydes (structural and stereo) = 1 ;

Total number of structurally isomeric aldehydes = 1 ;

Total number of isomeric carbonyl compounds (structural and stereo) = 1 ;

Total number of structurally isomeric carbonyl compounds = 1 ;

Total number of isomeric unsaturated alcohols (structural and stereo) = 1 ;

Total number of structurally isomeric unsaturated alcohols  = 1 ;

Total number of isomeric cyclic ethers (structural and stereo) = 1 ;

Total number of structurally isomeric cyclic ethers = 1 ;