See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Analysis of Stereoisomers in HOOC.CH=C=CH.COOH **Step 1: Identify the structure** The molecule is: $HOOC-CH=C=CH-COOH$ This contains a **cumulative double bond system** (allene): $CH=C=CH$ **Step 2: Recognize the geometric isomerism site** The central carbon in the allene system ($C=C=C$) is $sp$-hybridized. The two outer carbons are $sp^2$-hybridized and perpendicular to each other in 3D space. **Step 3: Determine possible configurations** For the substituents on the allene: - Left $CH$ group: attached to $COOH$ and one $H$ - Right $CH$ group: attached to $COOH$ and one $H$ The COOH groups can be oriented: - **Both on the same side** (cis) - **On opposite sides** (trans) This gives **2 geometric isomers** (diastereomers). **Step 4: Check for optical isomerism** The molecule has no chiral center (no carbon with 4 different groups), so it exhibits **no optical isomerism**. **Step 5: Conclusion** Only **2 geometric (cis-trans) isomers** are possible. **Answer: (B) two geometrical isomers**