Total number of structural isomers possible with the formula, C₄H₈ is ‘X’. Total number of acyclic isomers possible with the formula, C₄H₈ is ‘Y’. Difference between X and Y is

(1), (2), (3)--cis and trans….4 acyclic isomers….. 3 structural , 2 stereo;

(4), (5)--------- ---------------------------------two cyclic isomers…both structural ;

(1), (2), (3)--cis and trans, (4), (5)…..total six isomers ;