Write the structure and IUPAC names of all posible structural isomeric alkynes corresponding to `C_6H_(10)`. What type of strutural isomerism is exhibited by different pairs of isomers?
Strategy: First explore all the possibilities of placing the triple bond for the straight chain skeleton, followed by that for the branched chain skeleton with one side chain, and finally for the branched chain skeleton with two side chains.

Explanation

Stage I: `C-C-C-C-C-C`
(i). `underset("Hex-1-yne")(CH_(3)CH_(2)CH_(2)CH_(2)C-=CH)`
(ii). `underset("Hex-2-yne")(CH_(3)CH_(2)CH_(2)C-=CH-CH_(3))`
(iii). `underset("Hex-3-yne")(CH_(3)CH_(2)C-=C CH_(2)CH_(3))`
Stage II: `C-C-overset(C)overset(|)(C)-C-C`
(iv). `underset("3-Methylpent-1-yne")(HC-=C-underset(CH_(3))underset(|)(C)H-CH_(2)-CH_(3))`
Stage III: `C-C-C-overset(C)overset(|)(C)-C`
(v). `underset("4-Methylpent-1-yne")(HC-=C-CH_(2)-underset(CH_(3))underset(|)(C)H-CH_(3))` ltbr. (vi). `underset("4-Methylpent-2-yne")(CH_(3)-C-=C-underset(CH_(3))underset(|)(C)H-CH_(3))`
Stage IV: `C-C-underset(C)underset(|)overset(C)overset(|)(C)-C`
(vii). `underset("3,3-Dimethylbut-1-yne")(HC-=C-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(C)-CH_(3)`
Different pairs exhibit position and chain isomerism. For example, (i) and (ii) are position isomers (i) and (iv) are chain isomers, etc.