See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Analysis of Option (c) - Stability Order of Conjugate Acids **The conjugate acid stability order shown is INCORRECT.** ## Step-by-step reasoning: **Identify the species:** All three are conjugate acids of secondary amines (pyridinium derivatives with N-methylation). **Key principle:** The stability of conjugate acids $[B-H]^+$ depends on the basicity of the neutral base $B$. More basic bases give MORE stable conjugate acids. **Basicity comparison:** - **$N$-methylpiperidine** (left): Secondary amine with alkyl groups donating electron density to N - **$N$-methylmorpholine** (middle): Secondary amine WITH an electron-withdrawing oxygen in the ring - **$N$-methylpyrrolidine** (right): Secondary amine in a smaller ring (higher basicity due to greater s-character and nitrogen proximity) **Correct basicity order:** $$N\text{-methylpiperidine} > N\text{-methylpyrrolidine} > N\text{-methylmorpholine}$$ The oxygen atom in morpholine is strongly electron-withdrawing, making it the weakest base, hence its conjugate acid is LEAST stable. **The shown order is reversed:** The diagram claims left < middle < right, but it should be **right < middle < left** (or equivalently, the conjugate acid stability: right < middle < left). **Answer: Option (c) is INCORRECT.**