See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Resonance Contribution Analysis **For the first pair** ($CH_2=CH-OCH_3$): **Structure I** (neutral): $CH_2=CH-OCH_3$ - Normal covalent structure with $C=C$ double bond **Structure II** (charged): $\overline{CH_2}-CH=\oplus OCH_3$ - Oxygen donates electron pair to form positive charge - This is a valid resonance form since oxygen can expand its octet slightly through back-bonding - However, it creates formal charges that are unfavorable --- **For the second pair** ($CH_2=CH-NHCH_3$): **Structure I** (neutral): $CH_2=CH-NHCH_3$ - Normal structure with $C=C$ double bond **Structure II** (charged): $\overline{CH_2}-CH=\oplus NHCH_3$ - Nitrogen (less electronegative than oxygen) donates electron pair - Forms a more stable carbocation with resonance stabilization - Positive charge on $N$ is more easily accommodated than on $O$ due to lower electronegativity --- **Comparison:** Structure II in the **nitrogen case** is more stable and contributes more to the resonance hybrid because: - Nitrogen is less electronegative than oxygen - The lone pair on N is more available for donation - A positive charge on N is more acceptable than on O Therefore, Structure I (neutral form) contributes **less** in the nitrogen compound compared to the oxygen compound. **Answer: (C)** — I contributes less than II (in the nitrogen case).