Geometric or cis trans isomerism arises in an alkene because
Correct answer: A. the double bond prevents free rotation, fixing the groups on either side
- A. the double bond prevents free rotation, fixing the groups on either side
- B. the molecule contains a chiral carbon
- C. the double bond rotates freely
- D. alkenes contain a ring
Explanation
The pi bond locks the two carbons in a fixed relative orientation, so substituents are held either on the same side, cis, or on opposite sides, trans, and the two forms cannot interconvert without breaking the pi bond. Each doubly bonded carbon must also carry two different groups, otherwise the two arrangements are identical. Single bonds rotate freely, so alkanes show no such isomerism.
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About Isomerism
Isomerism occurs when compounds have the same molecular formula but different atom arrangements or spatial orientations. The content includes chain, position, functional, metameric and tautomeric isomerism, along with geometrical and optical isomerism, including cis-trans forms, E/Z notation, chirality and enantiomers.
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