The isomers of C7H14 are:
CH2=CHCH2CH2CH2CH2CH3
CH3CH=CHCH2CH2CH2CH3
CH3CH2CH=CHCH2CH2CH3
CH2=CHCH2CH2CH(CH3)CH3
CH2=CHCH2CH(CH3)CH2CH3
CH2=CHCH(CH3)CH2CH2CH3
CH2=C(CH3)CH2CH2CH2CH3
The above is but a sample of the isomers for C7H14. The structural arrangements are many. The first three are different from each other by the movement of the double bonds. The last four have six carbon chains in the longest chain and double bond between the first and second carbons. The double bonds within these last four structures could be moved within the straight chain to form different isomers, etc. Then we could form structures with five straight carbon chains and even four straight carbon chains with the double bond placement differing as we want it. The number of structural isomers realizable is therefore enormous.
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regards
Ramesh