How many isomers of butene are possible? What type of isomerism do they exhibit?

Explanation

Three structural isomers of butene are possible: `CH_(3)CH_(2)CH=CH_(2) " " ("But-1-ene"), " " CH_(3)CH=CHCH_(3) " " ("But-2-ene")and (CH_(3))_(2)C=CH_(2)` (2 - methylpropane). Again, but - 2 - ene exists as two gepmetrical isomers (diastereoisomers):

Hence, there are in total 4 isomers of butene: but - 1 - ene, cis but - 2 - ene, trans - but - 2 - ene, 2 - methylpropene.