JEE Main · 2024 · 31 Jan 2024 · Shift 2 · Hydrocarbons

Reactivity toward electrophilic aromatic substitution increases with the electron-donating strength of the ring substituent.

$-\mathrm{C}{\mathrm{H}}_3$ (compound B, toluene) donates electron density by hyperconjugation and induction (+I), strongly activating the ring.

Unsubstituted benzene (A) is the reference point.

$-\mathrm{Cl}$ (compound C, chlorobenzene) donates by resonance (+M) through a lone pair but withdraws more strongly by induction (−I) because of its high electronegativity; the net inductive effect dominates, making it weakly deactivating even though it remains ortho/para-directing.

$-\mathrm{N}{\mathrm{O}}_2$ (compound D, nitrobenzene) withdraws by both resonance and induction (−M, −I), making it strongly deactivating.

Reactivity order: $\mathrm{B}>\mathrm{A}>\mathrm{C}>\mathrm{D}$.