Total number of alkadienes (structural and stereo) possible with the formula, C5H8 is ‘X’. Total number of structurally isomeric isolated alkadienes possible with the formula, C5H8 is ‘Y’. Sum of X and Y is

Total number of alkadienes (structural and stereo)  = 8 ;Number of structurally isomeric alkadienes = 6 ;Number of  structurally isomeric conjugated alkadienes = 2 ;Number of  structurally isomeric cumulative alkadienes = 3 ;Number of  structurally isomeric isolated alkadienes = 1 ;Number of  structurally isomeric straight chain alkadienes = 4 ;Number of  structurally isomeric branched chain alkadienes = 2 ;Number of  stereo isomers (alkadienes only) = 4 ;Number of  geometrical isomers (alkadienes only) = 2 ;Number of  optical isomers (alkadienes only) = 2 ;Number of  enantiomeric pairs (alkadienes only) = 1 ;Number of structurally isomeric straight chain pentadienes = 4 ;Number of structurally isomeric branched chain butadienes = 2 ;Number of structurally isomeric branched chain propdienes = 0 ;*Cumulative dienes of the type (XY)C=C=C(XY) or (AB)C=C=C(XY)  are dissymmetric.They exhibit optical isomerism ;Ex : 2,3-pentadiene…(XY)C=C=C(XY) type where X = H , Y = CH3 :