See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Analysis of Contributing Structures in Nitroethene **Understanding Contributing Structures:** Contributing (resonance) structures stabilize molecules by delocalizing charge and electrons. More stable structures contribute significantly; less stable ones contribute minimally. **Evaluating Each Structure:** **(A)** $CH_2 = CH - \overset{+}{N}=\overset{-}{O}$ - Double bond between $C=C$ (strong $\pi$ bond) - Positive charge on N (moderately electronegative atom) - Negative charge on O (very electronegative, appropriate) - **Reasonably stable** ✓ **(B)** $CH_2 - \overset{+}{CH} - \overset{+}{N}$ - Two adjacent positive charges repel each other - Creates electrostatic destabilization - Less favorable but still has some contribution **(C)** $\overset{-}{CH_2} - \overset{+}{CH} - \overset{+}{N}$ - **Negative charge on carbon** (very poor, carbon is not electronegative) - Two positive charges still present - Negative charge placed on the least electronegative atom in the system - **Highly unfavorable and unstable** ✗ **(D)** $CH_2 - CH = \overset{+}{N}$ - Positive charge on N (acceptable) - $C=N$ double bond (good delocalization) - Better charge distribution than C **Answer: (C)** is the least contributing structure because it places negative charge on carbon—the least electronegative atom—which is electrostatically unfavorable and violates the principle that negative charge should reside on more electronegative atoms.