See image — Hydrocarbons Chemistry Question

💡 Solution & Explanation

Concept: Isomerization is a chemical process in which a compound is transformed into any of its isomers — molecules with the same molecular formula but a different arrangement of atoms. Step 1: Identify the reactant. The reactant is n-butane (CH3-CH2-CH2-CH3), a straight-chain alkane with 4 carbons. Step 2: Identify the product. The product is isobutane (2-methylpropane, CH3-CH(CH3)-CH3), a branched-chain alkane with 4 carbons. Step 3: Compare molecular formulas. Both n-butane and isobutane have the molecular formula C4H10. The carbon skeleton has been rearranged from a straight chain to a branched chain, but no atoms are added or removed. Step 4: Identify the reaction type. Since the molecular formula remains the same (C4H10) but the structural arrangement changes, this is a structural isomerization reaction. AlCl3 acts as a Lewis acid catalyst, and heat (Delta) drives the rearrangement. Step 5: Eliminate other options. - Polymerization: would involve combining multiple monomer units to form a larger molecule — molecular formula would increase dramatically. Not applicable here. - Cracking: would break larger molecules into smaller ones — the carbon count would decrease. Not applicable here since C4 → C4. - De-hydrogenation: would involve removal of hydrogen atoms to form alkenes or alkynes — the molecular formula would change (lose H2). Not applicable here. Therefore, the correct answer is A.