Final answer:
Propanol is the solvent among the given options that would lead to the fastest SN1 reaction because it is a polar protic solvent, which can stabilize the carbocation intermediate effectively.
Step-by-step explanation:
The solvent that would lead to the fastest SN1 reaction is propanol. SN1 reactions are nucleophilic substitution reactions where the rate determining step involves the formation of a carbocation intermediate. Solvents that are polar and protic (capable of forming hydrogen bonds) stabilize this intermediate and thereby accelerate the reaction.
In this scenario, n-hexane is a nonpolar solvent, benzene is also nonpolar, and tetrachloromethane (also known as carbon tetrachloride) is a polar aprotic solvent. Propanol, being a polar protic solvent, is best suited for SN1 reactions because it can solvate and stabilize the carbocation intermediate more effectively than the other options provided.