Which of the following substituent groups exerts both a negative inductive () effect and a positive — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

Halogens like fluorine ($-F$) are highly electronegative, meaning they withdraw electron density through the $\sigma$ -bond network ($-I$ effect). However, they possess lone pairs of electrons in p-orbitals, which they can donate into the conjugated $\pi$ system of the aromatic ring, thereby exerting a $+M$ (or $+R$) effect. Groups like $-NO_2$, $-CHO$, and $-COOH$ exert $-M$ effects.