Define substitution reactions. Why do arenes undergo substitution reaction even though they contain double bonds?

What happens when benzene is treated with :

${\mathrm{Br}}_2$ in presence of anhydrous ${\mathrm{AlCl}}_3$

What happens when benzene is treated with Conc. ${\mathrm{H}}_2{\mathrm{SO}}_4$ at $330 \mathrm{K}$?

What happens when benzene is treated with mixture of conc. ${\mathrm{H}}_2{\mathrm{SO}}_4$ and conc. ${\mathrm{HNO}}_3$ at $330\mathrm{K}?$