[tex]\bf HC\equiv C-C\equiv C-CH_2-C\equiv C-CH_3[/tex]
[tex]\bf CH_3-CH_2-C\equiv C-C\equiv C-C\equiv C-CH_2-CH_2-CH_2-CH_3[/tex]
[tex]\bf CH_3-CH_2-CH_2-C\equiv C-CH_2-CH_2-CH_2-CH_2-CH_2-CH_3[/tex]
[tex]\bf CH_3-CH_2-C\equiv C-CH_2-CH_2-CH_2-CH_2-CH_3[/tex]