The process that illustrates reformation of petroleum product is

Analyze the question: It asks which process is reforming (reformation) in petroleum refining.

Concept: Petroleum processing includes:

• Cracking: breaking large hydrocarbon molecules into smaller, more useful ones (e.g., hexane → butane + ethane).
• Reforming: rearranging the structure of hydrocarbon molecules, without significantly changing the number of carbons, to improve quality (e.g., a higher octane number for petrol). This often involves converting straight-chain alkanes or cycloalkanes into branched alkanes or aromatic compounds, using a catalyst such as platinum.
• Combustion: burning in oxygen to give CO₂ and water.
• Hydrogenation: adding H₂ across a double bond (alkene → alkane).

Check each option:

• A. Hexene to hexane: This adds hydrogen to a double bond, so it is hydrogenation, not reforming.
• B. Cyclohexane to benzene: C₆H₁₂ → C₆H₆ + 3H₂. The carbon number stays at 6, but the structure is rearranged into an aromatic ring (dehydrogenation). This is a typical catalytic reforming reaction, which is how aromatics are produced to improve petrol quality.
• C. Hexane to CO₂ and water vapour: This is complete combustion.
• D. Hexane to butane and ethane: C₆H₁₄ → C₄H₁₀ + C₂H₄ (or similar). A larger molecule breaks into smaller ones, so this is cracking.

Answer: B. Cyclohexane to benzene.

Tip: Remember the key words:

• Cracking = breaking big molecules into small ones.
• Reforming = reshaping molecules (same number of carbons, new structure, e.g., cycloalkane → aromatic or straight chain → branched).