1. Option A is the correct option.
Explanation: Phenol is more reactive than benzene towards electrophilic substitution reaction because the intermediate carbocation formed in reaction is more stabilised by phenol (5 resonating structures) by resonance stabilisation than benzene (2 resonating structures).
2. Option A is the correct option.
Explation: A rate of nitration of benzenes and hexadeuteriobenzene are different because C-D bond is stronger than C-H bond since mass of deuterium is twice that of hydrogen which gives strength in bonding.