The decreasing order of reactivity towards electrophilicsubstitution of the following compounds isA benzeneB chlorobenzeneC nitrobenzeneD methylbenzene Please explain how the reactivity depends

from left to right: phenol, toluene, benzene, fluorobenzene, and nitrobenzene.

From left to right, the amount of electron donation into the ring (activating the ring towards EAS) decreases. 

• OH is a σ donor (its HOMO is a σ bonding orbital), thereby activating the ring strongly.
• CH3 donates via hyperconjugation (from its C−H bonds), thereby activating the ring weakly.
• F is a decent π donor (filled p nonbonding orbitals) but is a good EWG, thereby deactivating the ring weakly.
• NO2 is a very strong EWG, thereby deactivating the ring strongly.

Therefore, from left to right, we have most to least reactive towards EAS.