Chapter 15, Problem 60P

A C−-D bond is harder to break than a C−-H bond, and, consequently, reactions in which C−-D bonds are broken proceed more slowly than reactions in which C−-H bonds are broken. What mechanistic information comes from the observation that perdeuterated benzene, $C_6{D}_6$, is nitrated at the same rate as normal benzene, $C_6{H}_6$ ?