The product of which of the following reactions undergoes hydrolysis by the $S_N 1$ mechanism?

The major product of the following reaction is:

Which of the following phrases are not correctly associated with $S_N1$ reaction?
$(1)$ Rearrangement is possible
$(2)$ Rate is affected by polarity of solvent
$(3)$ The strength of the nucleophile is important in determining rate
$(4)$ The reactivity series is tertiary $>$ secondary $>$ primary
$(5)$ Proceeds with complete inversion of configuration

The following order can be correct for:
$F^{-} > Cl^{-} > Br^{-} > I^{-}$

An alkene $X$ $(C_4H_8)$ on reaction with $HBr$ gave $Y$ $(C_4H_9Br)$. Reaction of $Y$ with benzene in the presence of anhydrous $AlCl_3$ gave $Z$,which is resistant to oxidation with $KMnO_4-KOH$. What are $X, Y, Z$ respectively?

Dehydrohalogenation in monohaloalkanes produces