Which of the following compounds will show geometric isomerism?

Options

A. Cyclohexene
B. Hex`-2-`ene
C. Hex`-3-`yne
D. `1,1-`Diphenylethylene

Answer

B

Explanation

Alkynes do not exhibit geometric isomerism as there is no barrier to free rotation because free rotation about a carbon-carbon triple bond can occur without distruption of the `pi` bond.
If the alkene is designated as ab`C=Cgh` then it will exist in two forms (diastereomers) so long as `a!=b` and `g!=h`. It does not matter whether `a` and//or `b` are the same as `g` and//or `h`. This type of steroisomerism is designated as cis-trans isomerism.
`underset(Hex-2-en e)(CH_(3)CH=CHCH_(2)CH_(3)`
It shows geometrical isomerism since each carbon atom of the double bond has two different substituents.