See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the structural environment of each hydrogen: From the structure drawn, the molecule contains two carbonyl (C=O) groups. Analyzing each labeled hydrogen: - H_a: Located on a terminal H2C= (vinyl/terminal alkene) carbon or a terminal sp3 CH2 group that is NOT adjacent to any carbonyl. This carbon is at the end of the chain with no electron-withdrawing group directly stabilizing its conjugate base. H_a is the least acidic. - H_b: Located on an sp3 carbon that is adjacent to ONE carbonyl group (alpha to one C=O). The conjugate base (carbanion) formed upon removal of H_b is stabilized by resonance with one C=O group. This makes H_b moderately acidic (pKa ~20). - H_c: Located on an sp3 carbon that is flanked by TWO carbonyl groups (alpha to two C=O groups, i.e., a 1,3-dicarbonyl active methine position). The conjugate base is stabilized by resonance with both C=O groups simultaneously, providing much greater stabilization. This makes H_c the most acidic (pKa ~9-13). Step 2 - Apply the principle of acidic strength: More electron-withdrawing groups adjacent to the C-H bond = greater stabilization of conjugate base = greater acidity. - H_c (alpha to 2 C=O groups): most acidic - H_b (alpha to 1 C=O group): moderately acidic - H_a (not alpha to any C=O, terminal carbon): least acidic Step 3 - Decreasing order of acidic strength: c > b > a Step 4 - Why other options fail: (a) a > b > c: Wrong, this reverses the correct order entirely. (b) b > a > c: Wrong, H_c should be most acidic, not least. (c) b > c > a: Wrong, H_c (doubly activated) must be more acidic than H_b (singly activated). (d) c > b > a: Correct, matches our analysis. Therefore, the correct answer is D.