What will be the rate of ${\mathrm{S}}_{\mathrm{N}}1$ Reaction?

The product in the following reaction is

$\mathrm{Ph}-\mathrm{Cl}+\mathrm{Fe}/{\mathrm{Br}}_2\to$ Product

Identify $\text{'}\mathrm{Z}\text{'}$ in the following reaction series,

${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2\mathrm{Br}\stackrel{\mathrm{aq}.\mathrm{NaOH}}{\to },\left(\mathrm{X}\right)\underset{\mathrm{Heat}}{\overset{{\mathrm{Al}}_2{\mathrm{O}}_3}{\to }}\left(\mathrm{Y}\right)\stackrel{{\mathrm{Cl}}_2/{\mathrm{H}}_2\mathrm{O}}{⟶}\left(\mathrm{Z}\right)$
 

Arrange the following compound in increasing order of reactivity towards aromatic nucleophilic substitution reaction.