Total number of structurally isomeric straight chain pentynes possible with the formula, C5H8 is equal to ‘X’.Total number of structurally isomeric alkynes containing tertiary carbon atoms possible with the formula, C5H8 is equal to ‘Y’. Sum of X and Y is

Total number of alkynes  = 3 ;Number of structurally isomeric alkynes = 3 ;Number of  structurally isomeric terminal alkynes = 2 ;Number of  structurally isomeric non terminal (internal) alkynes = 1 ;Number of  structurally isomeric straight chain alkynes = 2 ;Number of  structurally isomeric branched chain alkynes = 1 ;Number of  stereo isomers (alkynes only) = 0 ;Number of  enantiomeric pairs (alkynes only) = 0 ;Number of structurally isomeric straight chain pentynes = 2 ;Number of structurally isomeric branched chain butynes = 1 ;