See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Analysis of Isomerism Type **Step 1: Identify the molecular formula** Both compounds have the same molecular formula: $C_4H_8$ - Left structure: 4 carbons, 8 hydrogens - Right structure: 4 carbons, 8 hydrogens **Step 2: Analyze the carbon skeleton** Both have identical carbon chains: $C=C$ with methyl/hydrogen substituents at each end. The carbon framework is the same. **Step 3: Examine the key difference** The crucial difference is the **arrangement of groups around the double bond**: - **Left compound**: Both methyl groups are on the *same side* of the $C=C$ (cis configuration) - **Right compound**: Methyl and hydrogen are on *opposite sides* of the $C=C$ (trans configuration) **Step 4: Classify the isomerism** Since the isomers differ in spatial arrangement around a double bond (which restricts rotation), this is **Geometrical (or Stereoisomerism)**, not positional, chain, or functional group isomerism. **Answer: (2) Geometrical isomerism** These are *cis*-*trans* isomers (or *Z*-*E* isomers) of but-2-ene.