Write structures of different isomers corresponding to the 5th member of alkyne series. Also write IUPAC names of all the isomers. What type of isomerism is exhibited by different pairs of isomers?

Explanation

`5^(th)` Member of alkyne series is `C_(6)H_(10)` since first member is `C_(2)H_(2)`. The possible isomers and their IUPAC names are :
i) `HC-=C-CH_(2)-CH_(2)-CH_(2)-CH_(3)` Hex-1-yne
ii) `CH_(3)-C-=C-CH_(2)-CH_(2)-CH_(3)` Hex-2-yne
iii) `CH_(3)-CH_(2)-C-=C-CH_(2)-CH_(3)` Hex-3-yne
iv) `HC-=C-underset(CH_(3))underset(|)(CH)-CH_(2)-CH_(3)` 3-Methylpent-1-yne
v) `HC-=C-CH_(2)-underset(CH_(3))underset(|)(CH)-CH_(3)` 4-Methylpent-2-yne
vi) `CH_(3)-C-=C-underset(CH_(3))underset(|)(CH)-CH_(3)` 4-Methylpent-3-yne
vii) `HC-=C-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(C)-CH_(3)` 3,3-Dimethylbut-1-yne