See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Step 1 - Molecular formula analysis: Compound A has formula C6H12O3 with degree of unsaturation = (2×6 + 2 - 12)/2 = 1, indicating one degree of unsaturation (one C=O group). Step 2 - Iodoform test (I2/NaOH gives yellow precipitate): This indicates the presence of a CH3CO- (methyl ketone) group or a CH3CH(OH)- group. Since Tollens reagent gives no reaction with A directly (ruling out an aldehyde), the compound contains a methyl ketone (CH3C=O) group. Step 3 - No reaction with Tollens reagent directly: This confirms A is NOT an aldehyde. The carbonyl present must be a ketone. Step 4 - After hydrolysis, Tollens reagent gives silver mirror: This means hydrolysis of A generates an aldehyde. The acetal functional group -CH(OCH3)2 upon hydrolysis yields an aldehyde (-CHO). So A contains an acetal group that, upon hydrolysis, releases an aldehyde. Step 5 - Evaluating option (c): CH3-C(=O)-CH2-CH(OCH3)2 - Molecular formula: CH3CO (C2H3O) + CH2 (CH2) + CH(OCH3)2 (C3H7O2) = C2H3O + CH2 + C3H7O2 = C6H12O3. Check: C=6, H=3+2+7=12, O=1+2=3. Correct formula C6H12O3. - Contains CH3C=O group → positive iodoform test (yellow CHI3 precipitate). ✓ - The carbonyl is a ketone → no reaction with Tollens directly. ✓ - On hydrolysis: CH(OCH3)2 → CHO (aldehyde) + 2 CH3OH. The resulting aldehyde gives silver mirror with Tollens. ✓ Step 6 - Why other options fail: - Option (a): Contains a free -OH group adjacent to a ketone and an ether; upon hydrolysis it would not cleanly give a simple aldehyde for Tollens, and the structure does not fit neatly as an acetal. - Option (b): CH3-CO-C(OCH3)2-CH3 — hydrolysis of the acetal C(OCH3)2 gives a ketone (not aldehyde), so Tollens would not give silver mirror after hydrolysis. - Option (d): H-C(=O)-CH2-CH2-CH(OCH3)2 — contains an aldehyde directly, so Tollens reagent would react without hydrolysis, contradicting the observation of no Tollens reaction before hydrolysis. Also, no methyl ketone means no iodoform test. Therefore, the correct answer is C.