See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Step 1: Identify the molecular formula. Compound (A) has formula C11H8O. With a benzene ring (C6H5 = Ph), the remaining fragment is C5H3O, which must contain the CHO group plus additional unsaturation. Step 2: Interpret the ozonolysis result. Ozonolysis of (A) gives Ph—CHO (benzaldehyde) and compound 2b. Since the formula is C11H8O and Ph—CHO accounts for C7H6O, compound 2b must account for C4H2O (i.e., OHC—C≡C—CHO, glyoxal-type or a dialdehyde). 2b with Ag+ gives oxalic acid (HOOC—COOH), meaning 2b is glyoxal (OHC—CHO) or more precisely OHC—C≡C—CHO (but ozonolysis of a triple bond gives two carboxylic/aldehyde fragments). Actually, if 2b gives oxalic acid with Ag+ (Tollens oxidation), 2b must be glyoxal OHC—CHO, which oxidizes to HOOC—COOH (oxalic acid). Step 3: Determine the connectivity. Ozonolysis cleaves C=C double bonds. For Ph—CHO and OHC—CHO (glyoxal) to result from ozonolysis, compound (A) must contain a —CH=CH— linkage between Ph and a —C≡C—CHO fragment. Specifically, Ph—CH=CH—C≡C—CHO: ozonolysis cleaves the CH=CH double bond to give Ph—CHO and OHC—C≡C—CHO. The fragment OHC—C≡C—CHO (but-2-ynedial) upon treatment with Ag+ (Tollens) oxidizes to give oxalic acid (the triple bond is also oxidized under these conditions or the aldehyde groups are oxidized to give oxalic acid). This matches option (c). Step 4: Verify molecular formula for option (c): Ph—CH=CH—C≡C—CHO = C6H5—CH=CH—C≡C—CHO. Carbon count: 6+1+1+1+1+1 = 11. Hydrogen count: 5+1+1+0+0+1 = 8. Oxygen count: 1. Formula = C11H8O. ✓ Step 5: Verify it does not undergo self aldol condensation. The CHO in option (c) is an α,β-unsaturated aldehyde extended system, and there are no α-hydrogen atoms adjacent to the carbonyl (the carbon α to CHO is part of the triple bond C≡C, which has no H). Without α-hydrogens, self aldol condensation cannot occur. ✓ Step 6: Why other options fail: - (a) Ph—C≡C—C≡C—CHO: ozonolysis of triple bonds is not standard ozonolysis (O3 cleaves alkenes preferentially; alkynes react differently and would not cleanly give Ph—CHO). - (b) Ph—C≡C—CH=CH—CHO: ozonolysis of CH=CH gives Ph—C≡C—CHO and OHC—CHO. Ph—C≡C—CHO is not benzaldehyde, so this doesn't match. - (d) Ph—CH=CH—C=CH—CO2H: molecular formula does not match C11H8O (has two oxygens in CO2H) and product with Ag+ would not simply give oxalic acid. Therefore, the correct answer is C.