Assertion: Rates of nitration of benzene and hexadeuterobenzene are different. Reason: The C—H bond is stronger than the C—D bond.

Rates of nitration depends on the availability of electrophile, thus the rate of reaction is the same for both benzene and hexadeutero benzene. Thus the assertion is false. C-D bond is stronger than C-H bond since the atomic mass of deuterium is higher than that of hydrogen. The mass of an atom affects the vibration frequency, the heavier the atom, the lower the vibrational frequency, thus more energy needs to be supplied to break the bond. Thus the reason is also false. Hence, the correct option is (d). HYDROCARBONS 47