Total number of structurally isomeric alkynes with the formula, C₆H₁₀ is equal to ‘X’.Total number of structurally isomeric internal alkynes with the formula, C₆H₁₀ is equal to ‘Y’. Sum of X and Y is

Total number of alkynes (structural and stereo) = 8 ;

Number of structurally isomeric alkynes = 7 ;

Number of  structurally isomeric terminal alkynes = 4 ;

Number of  structurally isomeric non terminal (internal) alkynes = 3 ;

Number of  structurally isomeric straight chain alkynes = 3 ;

Number of  structurally isomeric branched chain alkynes = 4 ;

Number of  stereo isomers (alkynes only) = 2 ;

Number of  enantiomeric pairs (alkynes only) = 1 ;

Number of structurally isomeric straight chain hexynes = 3 ;

Number of structurally isomeric branched chain pentynes = 3 ;

Number of structurally isomeric branched chain butynes = 1 ;

*3-methyl-pent-1-yne has dextro and laevo forms