Define structural isomer and draw the isomeric structures of butane. Compare the structure of benzene and cyclohexane, by drawing them.

Explanation

Carbon compounds having same molecular formula but different structural formula are called structural isomers.
Example: butane `(C_4H_10)` shows the following two structural isomers
`H-underset(H)underset(|)overset(H)overset(|)(C )-underset(H)underset(|)overset(H)overset(|)(C )-underset(H)underset(|)overset(H)overset(|)(C )-underset(H)underset(|)overset(H)overset(|)(C )-underset(H)underset(|)overset(H)overset(|)(C )-H`
n - butane
`H-overset(H)overset(|)(C)-underset(H)underset(|)underset(H-C-H)underset(|)overset(H)overset(|)(C )-underset(H)underset(|)overset(H)overset(|)(C )-H`
Iso-butane
Structures of benzene and cyclocohexane

`{:("Benzene" C_6H_6 ,"Cyclohexane" C_6H_12),("Benzene has 6 carbon atoms","Cyclohexane has 6 carbon"),("and 6 hydrogen atoms".,"atoms and 12 hydrogen"),("Benzene has alternately","atoms. It does not consists"),("single and double bond","of double bond between"),("between carbon atoms. It","carbon atoms".),("has three double bonds",):}`
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