Total number of cyclic isomers possible with the formula, C4H6 is ‘X’. Total number of cyclic structural isomers (excluding bicyclo and spiro) possible with the formula, C4H6 is ‘Y’. Difference between X and Y is

Number of alkynes = 2 ;Number of terminal alkynes = 1 ;Number of non terminal (internal) alkynes = 1 ;Number of alkadienes = 2 ;Number of cumulative dienes = 1 ;Number of conjugated dienes = 1 ;Number of acyclic isomers = 4 ;Number of cycloalkenes = 4 ;Number of cyclic isomers = 4 ;Number of acyclic structural isomers = 4 ;Number of acyclic stereo isomers = 0 ;Number of cyclic structural isomers = 4 ;Number of cyclic stereo isomers = 0 ;Total number of  structural isomers = 8 ;Total number of  stereo isomers = 0 ;Total number of isomers = 8 ;