The number of alkyl halides which react faster than ${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{Cl}$ towards nucleophilic substitution $\left({\mathrm{S}}_{\mathrm{N}}2\right)$  is/are
${\left({\mathrm{CH}}_3\right)}_2{\mathrm{CHCH}}_2\mathrm{Cl},{\mathrm{C}}_6{\mathrm{H}}_5\mathrm{Cl},\text{\hspace{0.17em}}{\mathrm{CH}}_2={\mathrm{CHCH}}_2\mathrm{Cl},$
$\mathrm{p}-{\mathrm{NO}}_2{\mathrm{C}}_6{\mathrm{H}}_4\left({\mathrm{CH}}_2\mathrm{Cl}\right),{\mathrm{CH}}_3\mathrm{Cl},{\left({\mathrm{CH}}_3\right)}_3\mathrm{CCl},{\mathrm{CH}}_2=\mathrm{CHCl},\mathrm{o}-{\mathrm{CH}}_3{\mathrm{C}}_6{\mathrm{H}}_4\mathrm{Cl}$