See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Analysis of 1,3-Dichloroallene Isomerism **Structure:** $(CHCl)=C=CHCl$ (allene with two chlorine substituents) ## Step 1: Identify Geometrical Isomerism Allenes have **cumulated double bonds** ($C=C=C$). The two double bonds are perpendicular to each other: - The two $CHCl$ groups lie in perpendicular planes - If both $Cl$ atoms are on the same side → **cis isomer** - If $Cl$ atoms are on opposite sides → **trans isomer** This creates **geometric isomers** ✓ ## Step 2: Identify Optical Isomerism The middle carbon (central $C$ of allene) is bonded to two different groups: - Left: $CHCl$ group - Right: $CHCl$ group (different spatial orientation due to perpendicular planes) The two $CHCl$ groups occupy perpendicular planes, making the central carbon an **asymmetric center**. This generates **optical isomers** (enantiomers) ✓ ## Step 3: Conclusion Since 1,3-dichloroallene exhibits: - **Geometrical isomerism** (cis-trans about the allene) - **Optical isomerism** (chiral allene axis) **Answer: (C) both (A) and (B)** ✓