Saturated vs. Unsaturated Hydrocarbons

Steps:

• Identify X as saturated C4H10 (butane) and Y as unsaturated, e.g., C4H8 (butene).
• Evaluate statement 1: Unsaturated Y has double bonds, enabling polymerization under suitable conditions.
• Evaluate statement 2: Both combust to 4 CO2 per mole (C4 basis), so Y does not produce more CO2.
• Evaluate statement 3: Y (C4H8) has fewer H atoms than X (C4H10), so statement is false.

Why A is correct:

• Only statement 1 holds, as alkenes polymerize via addition reactions, per organic chemistry definitions.

Why the others are wrong:

• B: Statement 3 is false; unsaturated compounds have fewer hydrogens (general formula CnH2n vs. CnH2n+2).
• C: Includes false statement 2; CO2 yield equals carbon atoms combusted (4 mol CO2 each).
• D: Both 2 and 3 are false for reasons above.

Final answer: A