The S_N² reaction is opposed by hindered substrates, non￾basic nucleophiles, and protic solvents

The reaction of the tertiary halide (CH₃)₃ CBr with neutral water is more than 1 million times as fast as the corresponding reaction of the methyl halide CH₃Br.
This alternative mechanism is called the S_N¹ reaction (for substitution, nucleophilic, unimolecular).

The observation of first-order kinetics for the S_N¹ reaction of (CH₃)₃ CBr with water tells us that the alkyl halide is involved in a unimolecular rate-limiting step. In other words, 2-bromo-2-methylpropane undergoes some manner of spontaneous, rate-limiting reaction without involvement of the nucleophile. But because the nucleophile must be involved at some point, there must be at least two steps in the reaction.

Answer the following questions on the basis of above write up