Final answer:
The statement that the SN2 reaction rate of (R)-2-bromobutane with sodium cyanide is independent of the solvent is not true, as the solvent does affect the rate of the reaction.
Step-by-step explanation:
The correct statement regarding the SN2 reaction of (R)-2-bromobutane with sodium cyanide is that the statement claiming the rate of the reaction is independent of the identity of the solvent is not true. In an SN2 reaction, the rate is bimolecular, which means it is dependent on both the concentration of the nucleophile, in this case, sodium cyanide, and the substrate, which is (R)-2-bromobutane. The rate of reaction is indeed proportional to the concentrations of both these reactants. However, the identity and properties of the solvent can significantly affect the reaction rate, as the solvent can stabilize or destabilize the transition state or reactants. Hence, the SN2 reaction proceeds with inversion of configuration, and the rate is definitely affected by the solvent used.