See image — Hydrocarbons Chemistry Question

💡 Solution & Explanation

Concept: Ozonolysis cleaves C=C double bonds. For cumulated dienes (allenes, C=C=C), ozonolysis of each double bond produces carbonyl fragments, with the central carbon of the allene giving CO2 (since it is doubly bonded to both sides and has no H or alkyl group attached when cleaved from both sides). Step 1: Identify the molecular formula. C4H6 has degree of unsaturation = (2×4+2-6)/2 = 2, indicating two degrees of unsaturation (e.g., two double bonds or a ring plus one double bond). Step 2: Analyze option (b) CH3-CH=C=CH2 (1,2-butadiene, an allene). This molecule has two cumulated double bonds: one between C2 and C3, and one between C3 and C4. Step 3: Ozonolysis of the C3=C4 double bond: CH2= end gives HCHO (formaldehyde), and the central carbon C3 retains a double bond to C2 side → C3 fragment becomes O=C=CH-CH3 (an intermediate). Step 4: Ozonolysis of the C2=C3 double bond of that intermediate: CH3-CH= gives CH3CHO (acetaldehyde), and =C= (the central carbon with no H or substituents remaining) gives CO2. Step 5: Products from (b): HCHO + CO2 + CH3CHO — exactly matches the given products HCHO, CO2, CH3CHO. ✓ Step 6: Why option (a) fails: H2C=CH-CH=CH2 (1,3-butadiene) on ozonolysis would give 2 equivalents of HCHO and 1 equivalent of OHC-CHO (glyoxal), not CO2 or CH3CHO. ✗ Therefore, the correct answer is B.