Assertion: Phenol is more reactive than benzene towards electrophilic substitution reaction.

Reason: In the case of phenol, the intermediate carbocation is more resonance stabilized.

Explanation:

Introduction:
Phenol (C6H5OH) and benzene (C6H6) are both aromatic compounds, but phenol contains a hydroxyl (-OH) group attached to the benzene ring. This hydroxyl group in phenol increases its reactivity towards electrophilic substitution reactions compared to benzene.

Resonance Stabilization:
The resonance stabilization of the intermediate carbocation is one of the main factors determining the reactivity of phenol towards electrophilic substitution reactions.

Resonance in Phenol:
In phenol, the lone pair of electrons on the oxygen atom can delocalize into the benzene ring through resonance. This delocalization of electrons creates a resonance-stabilized intermediate carbocation during electrophilic substitution reactions. The resonance structures of phenol can be represented as follows:

Ph-OH ↔ Ph+ ↔ Ph-OH

The positive charge on the benzene ring can be delocalized over the entire ring due to resonance, making the intermediate carbocation more stable. This resonance stabilization lowers the energy of the intermediate and increases the reactivity of phenol towards electrophilic substitution reactions.

Resonance in Benzene:
In the case of benzene, there is no substituent to stabilize the intermediate carbocation through resonance. Therefore, the intermediate carbocation in benzene is less stable compared to phenol. This leads to lower reactivity of benzene towards electrophilic substitution reactions.

Conclusion:
In conclusion, the assertion that phenol is more reactive than benzene towards electrophilic substitution reactions is true. The reason behind this is the resonance stabilization of the intermediate carbocation in phenol, which is absent in benzene. The resonance stabilization in phenol lowers the energy of the intermediate, making it more reactive towards electrophilic substitution reactions.