See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

## R Power (Resonance Power) Ranking **R power** refers to the electron-donating ability of a group through resonance effects. ### Analysis of Each Group: **(1) $-O^-$ (Alkoxide ion)** - Oxygen with negative charge: most electronegative element with excess electrons - Strongest resonance donation via lone pairs - **Highest R power** **(2) $-NH_2$ (Amino group)** - Nitrogen with lone pair donates via resonance - Strong electron donor, but less effective than $O^-$ - **Second highest** **(3) $-OH$ (Hydroxyl group)** - Oxygen with lone pair donates, but less than $NH_2$ (nitrogen is less electronegative) - Weaker than $-NH_2$ due to competing inductive withdrawal by O - **Third** **(4) $-NHCOCH_3$ (Acetamido group)** - Resonance donation is suppressed by the electron-withdrawing carbonyl group - The C=O pulls electron density away from N, reducing N's ability to donate - **Weakest R power** ### Correct Order: $$\boxed{(1) > (2) > (3) > (4)}$$ **Option B is correct** because the R power follows: $-O^- > -NH_2 > -OH > -NHCOCH_3$, reflecting the decreasing electron-donating ability through resonance.