Total number of stereo isomers (alkynes only) possible with the formula, C5H8 is equal to ‘X’. Total number of enantiomeric pairs (alkadienes only) 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 :  Total number of alkynes  = 3 ;Total number of stereo isomers (alkynes only) = 0 ;Total number of enantiomeric pairs (alkynes only) = 0 ;