Question

The number of geometrical isomers possible for the compound, CH$_3$CH = CH - CH = CH$_2$ is:

• A. 2
• B. 3
• C. 4
• D. 6

Hint:

For cis-trans isomerism, each carbon in the double bond must have two different substituents.

Answer 1

The Correct Option is A

Step 1: Identification of Double Bonds
The compound contains two double bonds.
The presence of two different substituents on each carbon atom of a double bond is crucial for geometrical isomerism.
Step 2: Assessment of Geometrical Isomerism Potential
The double bond between \( {C}_2 \) and \( {C}_3 \) has distinct substituents, enabling cis-trans isomerism.
The double bond between \( {C}_4 \) and \( {C}_5 \) features two identical hydrogen atoms, thus precluding cis-trans isomerism.
Step 3: Determination of Isomer Count
Geometrical isomerism is exhibited by only one of the double bonds.
Consequently, there are precisely two geometrical isomers.
Therefore, the correct option is (A).