Correct answer: SN2 and SN1
The first reaction involves a strong nucleophile (C2H5OH) attacking the substrate, leading to an SN2 mechanism where the nucleophile displaces the leaving group in a single concerted step. In the second reaction, the nucleophile (C2H5O−) attacks the substrate more effectively due to its stronger nucleophilicity, but the presence of the leaving group allows for a carbocation intermediate, characteristic of an SN1 mechanism.