Chlorobenzene is extremely less reactive towards a nucleophilic substitution reaction. Give two reasons for the same.
 

Arrange the compounds of each set in the order of reactivity towards ${\mathrm{S}}_{\mathrm{N}}2$ displacement. 1-bromo-3-methylbutane, 2-bromo-2-methylbutane, 2-bromo-3-methylbutane.

Arrange the compounds of each set in the order of reactivity towards ${\mathrm{S}}_{\mathrm{N}}2$ displacement: 1-bromobutane, 1-bromo-2, 2-dimethylpropane, 1-bromo-2-methylbutane, 1-bromo-3-methylbutane.