JEE Main · 2023 · 15 Apr 2023 · Shift 1 · Hydrocarbons

Reactivity in electrophilic aromatic substitution increases with the electron density of the ring. The dimethylamino group of N,N-dimethylaniline (e) is the strongest electron donor by resonance and activates the ring most. The methoxy group of anisole, compound (d), is a resonance donor too but weaker than nitrogen, placing it next. A methyl group activates only weakly through hyperconjugation and induction, so toluene (a) follows, and unsubstituted benzene (b) sets the baseline. The trifluoromethyl group of (c) withdraws electrons strongly by induction and deactivates the ring most. The decreasing order of reactivity is $e>d>a>b>c$.