See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

Concept: A stronger acid has a more stable conjugate base (weaker conjugate base). Conversely, a weaker acid has a less stable (stronger) conjugate base. We need to identify which compound in each pair is the WEAKER acid, because it will have the STRONGER conjugate base. Pair A: H2S (1) vs H2O (2) - H2O has pKa ≈ 15.7; H2S has pKa ≈ 7. - H2S is a stronger acid than H2O. - Therefore H2O (2) is the weaker acid and has the stronger conjugate base (OH⁻ is a stronger base than HS⁻). - Answer for this pair: 2 Pair B: Compound 3 (glutarimide, with two flanking C=O groups on the NH) vs Compound 4 (delta-valerolactam, with one C=O group on the NH) - In compound 3, the NH proton is flanked by two carbonyl groups, making the nitrogen much more acidic due to double resonance stabilization of the conjugate base anion. - In compound 4, only one carbonyl stabilizes the conjugate base, so compound 4 is a weaker acid. - Therefore compound 4 has the stronger conjugate base. - Answer for this pair: 4 Pair C: CH3C≡CH (5, propyne) vs CH3CH=CH2 (6, propene) - sp carbon in propyne is more electronegative than sp2 carbon in propene, making the terminal alkyne C-H more acidic (pKa ≈ 25 for terminal alkyne vs pKa ≈ 43 for alkene C-H). - Propyne (5) is more acidic; propene (6) is less acidic. - Therefore propene (6) has the stronger conjugate base. - Answer for this pair: 6 Combining: the compounds with stronger conjugate bases are 2, 4, 6. Why other options fail: - (b) 1, 3, 5: These are the stronger acids in each pair, so they have weaker conjugate bases. - (c) 2, 3, 5: Compound 3 is more acidic than 4 (not less), and compound 5 is more acidic than 6. - (d) 1, 3, 6: Compound 1 (H2S) is more acidic than H2O, and compound 3 is more acidic than 4. Therefore, the correct answer is A.