Chong Ka Shing's answer to Germaine's Junior College 2 H3 Maths Singapore question.

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Chong Ka Shing
Chong Ka Shing's answer
8 answers (A Helpful Person)
1st
1-butene and 2-butene are isomers with different positioning of the functional group and molecular formula of C4H8. Under the same functional group, there is also branching of C4H8 to create the 2-Methylpropene isomer.

Additionally C4H8 can be cycloalkanes like cyclobutane and methylcyclopropane. Thus, in total there are 5 isomers for 1-butene and 2-butene.